Submerged forests

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SUBMERGED FORESTS

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PREFACE

TT^NOWLEDGE cannot be divided into compart-
ments, each given a definite name and allotted
to a different student. There are, and always must
be, branches of knowledge in which several sciences
meet or have an interest, and these are somewhat
liable to be neglected. If the following pages arouse
an interest in one of the by-ways of science their
purpose has been fulfilled.

C. R.

February 17, 1913.

90881

^

CONTENTS

CHAP.

PAGE

Preface

V

I.

Inti'oductory

1

II.

The Thames Valley ....

11

III.

The East Coast ....

19

IV.

The Dogger Bank ....

39

V.

The Irish Sea and the Bristol Channel

50

VI.

The English Channel

64

VII.

Cornwall and the Atlantic Coast .

80

VIII.

Summary

105

Bibliography

122

Index

125

LIST OF ILLUSTRATIONS

FIG. PAGE

Buried Forest seen at low-water at Dove Point,
on the Cheshire coast. (From the Cambridge
County Geography of Cheshire) . . frontispiece

1. Diagi-am to show the relations of the Submerged

Forests to the sea-level 7

2. Section at Tilbury Docks 14

3. Section across the Humber bet\veen Hessle and

Barton 36

4. Approximate Coast-line at the period of the

lowest Submerged Forest .... 40

CHAPTER I

INTRODUCTORY

Most of our sea-side places of resort lie at the
mouths of small valleys, which originally gave the
fishermeu easy access to the shore, and later on
provided fairly level sites for building. At such
places the fishermen will tell you of black peaty
earth, with hazel-nuts, and often with tree-stumps
still rooted in the soil, seen betAveen tide-marks when
the overlying sea-sand has been cleared away by
some storm or unusually persistent wind. If one is
fortunate enough to be on the spot when such a
patch is uncovered this " submerged forest " is found
to extend right down to the level of the lowest tides.
The trees are often well-grown oaks, though more
commonly they turn out to be merely brush-wood of
hazel, sallow, and alder, mingled with other swamp-
plants, such as the rhizomes of Osmunda.

These submerged forests or "Noah's Woods" as
they are called locally, have attracted attention from
early times, all the more so owing to the existence
of an uneasy feeling that, though like most other

u. 1

2 SUBMERGED FORESTS [ch.

geological phenomena they were popularly explained
by Noah's deluge, it was difficult thus to account for
trees rooted in their original soil, and yet now found
well below the level of high tide.

It may be thought that these flats of black peaty
soil though curious have no particular bearing on
scientific questions. They show that certain plants
and trees then lived in this country, as they do now ;
and that certain animals now extinct in Britain once
flourished here, for bones and teeth of wild-boar,
wolf, bear, and beaver are often found. Beyond this,
however, the submerged forests seem to be of little
interest. They are particularly dirty to handle or
walk upon ; so that the archaeologist is inclined to
say that they belong to the province of geology, and
the geologist remarks that they are too modern to be
worth his attention ; and both pass on.

Should we conquer our natural repugnance for
such soft and messy deposits, and examine more
closely into these submerged forests, they turn out
to be full of interest. It is largely their extremely
inconvenient position, always either wet or submerged,
that has made them so little studied. It is necessary
to get at things more satisfactorily than can be done
by kneeling do^^n on a wet muddy foreshore, with
the feeling that one may be caught at any time by
the advancing tide, if the study is allowed to become
too engrossing. But before leaving for a time the

I] INTRODUCTORY 3

old land-surface exposed between tide marks, it will
be well to note that we have already gained one
piece of valuable information from this hasty traverse.
We have learnt that the relative level of land and
sea has changed somewhat, even since this geologically
modern deposit was formed.

Geologists, however, sometimes speak of the sub-
merged forests as owing their present position to
various accidental causes. Landslips, compression of
the underlying strata, or the removal of some pro-
tecting shingle-beach or chain of sand-dunes are all
called into play, in order to avoid the conclusion that
the sea-level has in truth ciianged so recently. The
causes above mentioned have undoubtedly all of
them affected certain localities, and it behoves us to
be extremely careful not to be misled. Landslips
cannot happen without causing some disturbance,
and a careful examination connnonly shows no sign
of disturbance, the roots descending unbroken into
the rock beloAv. It is also evident in most cases that
no landslip is possible, for the "forest" occupies a
large area and lies nearly level.

Compression of the underlying strata, and conse-
quent sinking of the land-surface above, is however
a more difficult matter to deal with. Such com-
pression undoubtedly takes place, and some of the
appearances of subsidence since the Roman invasion
are really cases of this sort. AVhere the trees of the

1—2 .

4 SUBMERGED FORESTS [ch.

submerged forest can be seen rooted into hard rock,
or into firm undisturbed strata of ancient date, there
can, however, be no question that their position below
sea-level is due to subsidence of the land or to a rise
of the sea, and not to compression. But in certain
cases it is found that our submerged land-surface
rests on a considerable thickness of soft alluvial
strata, consisting of alternate beds of silt and
vegetable matter. Here it is perfectly obvious that
in course of time the vegetable matter will decay,
and the silt will pack more closely, thus causing the
land-surface above slowly to sink. Subsidence of
this character is well known in the Fenland and in
Holland, and we must be careful not to be misled by
it into thinking that a change of sea-level has hap-
pened within the last few centuries. The sinking of
the Fenland due to this cause amounts to several feet.

The third cause of uncertainty above mentioned,
destruction of some bank which formerly protected
the forest, needs a few words. It is a real difficulty
in some cases, and is very liable to mislead the
archaeologist. We shall see, however, that it can
apply only to a very limited range of level.

Extensive areas of marsh or meadow, protected
by a high shingle-beach or chain of sand-dunes, are
not unconnnon, especially along our eastern coast.
These marshes may be (piite fresh, and even have
trees growing on them, below the level of high tide,

I] INTRODUCTORY

as long as the barrier remains unbroken. The reason
of this is obvious. The rise and fall of the tide allows
sea water to percolate landward and the fresh water
to percolate seaward ; but the friction is so great as
to obliterate most of the tidal wave. Thus the sea at
high tide is kept out, the fresh water behind the
barrier remaining at a level slightly above that of
mean tide, and just above that level we may find
a wet soil on which trees can grow. But, and here is
the important point, a protected land-surface behind
such a barrier can never lie below the level of mean
tide ; if it sinks below that level it must immediately
be flooded, either by fresh water or by sea water.
Tins rule applies everywhere, except to countries
where evaporation exceeds precipitation ; only in
such countries, Palestine for instance, can one find
sunk or Dead Sea depressions below mean-tide level
of the open sea.

The submerged forest that we have already
examined stretched far below the level of mean tide,
in fact we followed it down to the level of the lowest
spring tides. Nothing but a change of sea-level ^vill
account for its present position. In short, the three
objections above referred to, while teaching us to be
careful to examine the evidence in doubtful cases,
cannot be accepted as any explanation of the con-
stant and widespread occurrence of ancient land-
surfaces passing beneath the sea.

6 SUBMERGED FORESTS [ch.

We have thus traced the submerged forest down
to low-water mark, and have seen it pass out of our
reach below the sea. We naturally ask next, Wliat
happens at still lower levels ? It is usually difficult
to examine deposits below the sea-level ; but for-
tunately most of our docks are excavated just in
such places as those in whicli the submerged forests
are likely to occur. Docks are usually placed in the
wide, open, estuaries, and it is often necessary
nowadays to carry the excavations fully fifty feet
below the marsh-level. Such excavations should be
carefully watched, for they throw a flood of light
on the deposits we wish to examine.

Every dock excavation, however, does not neces-
sarily cut through the submerged forests, for channels
in an estuary are constantly shifting, and many of
our docks happen to be so placed as to coincide with
comparatively modern silted-up channels. Thus at
Kings Lynn they hit on an old and forgotten channel
of the Ouse, and the bottom of the dock showed a
layer of ancient shoes, mediaeval pottery, and such-
like— interesting to tlic archaeologist, but not what
we are now in search of At Devonport also the
recent dock extension coincided with a modern
silted-up channel. In various other cases, however,
the excavations have cut through a most curious
alternation of deposits, though the details vary from
place to place.

I]

INTRODUCTORY

The diagram (fig. 1) shows roughly what is found.
We will suppose that the docks are placed, as is
usually the case, on the salt marshes, but with their
landward edge reaching the more solid rising ground,
on which the warehouses, etc., are to be built. Be-
ginning at or just above the level of ordinary high-
water of spring tides, the first deposit to be cut
through is commonly a bed (A) of estuarine silt or
warp with remains of cockles, ScrohiGidaria, and
salt-marsh vegetation. Mingled with these we find

?fli^ej of iligh.Watfp
Level of Low Water

H ?(S Iff. *-«-*

Fig. 1.

drifted wreckage, sunk boats, and miscellaneous
rubbish, all belonging to the historic period. The
deposits suggest no change of sea-level, and are
merely the accumulated mud which has gradually
blocked and silted up great part of our estuaries and
harbours during the last 3500 years.

This estuarine silt may continue dowuAvard to a
level below mean tide, or perhaps even to low-water
level ; but if the sequence is complete we notice
below it a sudden change to a black peaty soil {B),

8 SUBMERGED FORESTS [ch.

fiill of vegetable matter, showing sallows, alder, and
hazel rooted in their position of growth. In this soil
we may also find seams of shell-marl, or chara-marl,
such as would form in shallow pools or channels in a
freshwater marsh. This black peaty soil is obviously
the same " submerged forest " that we have already
examined on the foreshore at the mouth of the
estuary ; the only difference being that in the more
exposed situation the waves of the sea have cleared
away the overlying silt, thus laying bare the land
surface beneath. In the dock excavations, therefore,
the submerged forest can be seen in section and
examined at leisure.

The next deposit (C), lying beneath the submerged
forest, is commonly another bed of estuarine silt,
extending to a depth of several feet and carrying our
observations well below the level of low-water. Then
comes a second land-surface (Z>), perhaps with trees
differing from those of the one above ; or it may be
a thick layer of marsh peat. More silt (E) follows ;
another submerged forest (if^) ; then more estuarine
deposits {G) ; and finally at the base of the channel,
fully 50 feet below the level of high-water, we may
find stools of oak {H) still rooted in the undisturbed
rock below.

As each of these deposits conunonly extends con-
tinuously across the dock, except where it happens
to abut against the rising ground, it is obvious that

I] INTRODUCTORY 9

it is absolutely cut off from each of the others. The
lowest land-surface is covered by laminated silts, and
that again is sealed up by the matted vegetation of
the next growth. Thus nothing can work its way
down from layer to layer, unless it be a pile forcibly
driven down by repeated blows. Materials from the
older deposits in other parts of the estuary may
occasionally be scoured out and re-deposited in a
newer layer ; but no object of a later period will find
its way into older beds.

Thus we have in these strongly marked alterna-
tions of peat and warp an ideal series of deposits
for the study of successive stages. In them the
geologist should be able to study ancient changes of
sea-level, under such favourable conditions as to
leave no doubt as to the reality and exact amount
of these changes. The antiquary should find the
remains of ancient races of man, sealed up with his
weapons and tools. Here he Avill be troubled by
no complications from rifled tombs, burials in older
graves, false inscriptions, or accidental mixture. He
ought here to find also implements of wood, basket-
work, or objects in leather, such as are so rarely
preserved in deposits above the water-level, except
in a very dry country.

To the zoologist and botanist the study of each
successive layer should yield evidence of the gradual
changes and fluctuations in our fauna and flora.

10 SUBMERGED FORESTS [CH.

during early periods when man, except as hunter,
liud little influence on the face of nature. If I can
persuade observers to pay more attention to these
modern deposits my object is secured, and we shall
soon know more about some very obscure branches
of geology and archaeology.

I do not wish to imply that excellent work has
not already been done in the examination of these
deposits. Much has been done ; but it has usually
been done unsystematically, or else from the point
of view of the geologist alone. What is wanted is
something more than this — the deposits should be
examined bed by bed, and nothing should be over-
looked, whether it belong to geology, archaeology, or
natural history. We desire to know not merely what
was the sea-level at each successive stage, but what
were the climatic conditions. We must enquire also
what the fauna and flora were like, what race of
man then inhabited the country, how he lived, what
weapons and boats he used, and how he and all these
animals and plants were able to cross to this country
after the passing away of the cold of the Glacial
period.

To certain of the above questions we can already
make some answer; but before dealing with con-
clusions, it will be advisable to give some account
of the submerged land-surfaces known in various
parts of Biitain. This we will do in the next chapters.

II] THE THAMES VALLEY 11

Before going fiirtlier it will be well to explain
and limit more definitely the field of our present
enquiry. It may be said that there are " submerged
forests " of various geological dates, and this is per-
fectly true. The " dirt-bed " of the Isle of Purbeck,
with its upright cycad-stems, was at one time a true
submerged forest, for it is overlain by various marine
strata, and during the succeeding Cretaceous period
it was probably submerged thousands of feet. Every
coal seam with its underlying soil or " underclay "
penetrated by stigmarian roots was also once a sub-
merged forest. L^sage, however, limits the term to
the more recent strata of this nature, and to these
we will for the present confine our attention. We
do not undertake a description of the earlier Cromer
Forest-bed, or even of the Pleistocene submerged
forests containing bones of elephant and rhinoceros
and shells of Corbicula fiumlnaUs. These deposits
will, however, be referred to where from their position
they are liable to be confounded with others of later
date.

CHAPTER II

THE THAMES VALLEY

In the last chapter an attempt was made to give
a general idea of the nature of the deposits ; we will
now give actual examples of what has been seen.

12 SUBMERGED FORESTS [ch.

Unfortunately we cannot say " what can be seen," for
the lower submerged forests are only visible in dock
excavations. As these works are carried well below
the sea-level and have to be kept dry by pumping,
it is impossible for them to remain open long, and
though new excavations are constantly being made,
the old ones are nearly always hidden within a few
weeks of their becoming visible. Of course these
remarks do not apply to the highest of these sub-
merged land-surfaces, which can be examined again
and again between tide-marks, whenever the tide is
favourable and the sand of the foreshore has been
swept away.

The most convenient way of dealing with the
evidence will perhaps be to describe first what has
been seen in the estuary of the Thames. Then in
later chapters we will take the localities on our east
coast and connected Avith the Xorth Sea basin. Next
we will speak of those on the Irish Sea and English
Channel. Lastly, the numerous exposures on the
west or Atlantic coast will require notice, and with
them may be taken the corresponding deposits on
the French coast. Each of these groups will require
a separate chapter.

The Thames near London forms a convenient
starting point, for the numerous dock-excavations,
tunnels, deep drains and dredgings have laid open
the structure of this valley and its deposits in an

II] THE THAMES VALLEY 13

exceptionally complete way. The published accounts
of the excavations in the Thames Valley are so
voluminous that it is impossible here to deal with
them in any detail ; we must therefore confine our-
selves to those which best illustrate the points we
have in view, choosing modern excavations which
have been carefully watched, noted, and collected
from rather than ancient ones.

We cannot do better than take as an illustration
of the mode of occurrence and levels of the sub-
merged land-surfaces the section seen in the ex-
cavation of Tilbury Docks, for this was most carefully
noted by the engineers, and was visited by two com-
petent observers, Messrs. W. Whitaker and F. C J.
Spurrell. This excavation is of great scientific
importance, for it led to the discovery of a human
skeleton beneath three distinct layers of submerged
peat, and these remains have been most carefully
studied by Owen and Huxley, and more recently by
Professor Keith.

The section comnmnicated to Sir Richard Owen
by Mr Donald Baynes, the engineer superintending
the excavation at the time of the discovery, is shown
in the diagram on p. 14. As Mr Baynes himself saw
part of the skeleton in the deposit, his measured
section is most important as showing its exact re-
lation to the submerged forests. It is also well
supplemented by the careful study of the different

Trinity High Water Level

8

Water 6'- 77

"R

Clay 6' 04

Mud 10'- 76

]\Iarsh Level

Mud and Peat I'vTO

Peat r 08

Mud 3'-88

Peat 3' -58

Mud r-76

Sand &Beconip'jsed Wood ■C,2[ i

1:^

Sand 12'-47

10

Mud and Peat 3' "24

u-5

Level at which human re-
mains were found

Bal)a«» Gravel

Fig. 2. Section at Tilbury Docks.

CH. II] THE THAMES VALLEY 15

layers made by Mr Spurrell, for though his specimens
did not come from exactly this part of the docks, the
various beds are traceable over so large an area that
there is no doubt as to their continuity.

Owen thought that this skeleton belonged to a
man of the Palaeolithic period, considering it con-
temporaneous with the mammoth and rhinoceros
found elsewhere in the neighbourhood. Other geo-
logical writers showed how^ever that these deposits
were much more modern, and some of them spoke
somewhat contemptuously of their extremely recent
date. But Huxley saw the importance of this " river-
drift man" as an ancient and peculiar race, and
Professor Keith has more recently drawn especial
attention to the well-marked characteristics of the
type. The skeleton is not of Palaeolithic date, but
neither is it truly modern ; other examples have
turned up in similar deposits elsewhere.

We will now describe more fully the successive
layers met with in Tilbury Docks, condensing the
account from that given by Messrs. Spurrell and
Whitaker, and using where possible the numbers
attached by the engineer to the successive beds.

It will be noticed that the marsh-level lies several
feet below Trinity high water. Below the sod of the
marsh came a bed of fine grey tidal clay (1), in which
at a depth of seven feet below the surface Mr Spurrell
noted, in one part of the docks, an old grass-grown

16 SUBMERGED FORESTS [ch.

surface strewn with Roman refuse, such as tiles,
pottery, and oyster shells. This fixes the date of
the layer above as post-Roman ; but the low position
of the Roman land-surface, now at about mean-tide
level, is due in great part to shrinkage since the
marsh was embanked and drained— it is unconnected
with any general post-Roman subsidence of the land.
Beneath tlie Roman layer occurs more marsh-clay
and silt (2), resting on a thin peat (4) which according
to Mr AMiitaker is sometimes absent. Then follows
another bed of marsh-clay (5), shown by the engineer
as four feet thick, but which in places thickens to
six or seven feet. Below this is a thick mass (6) of
reedy peat (the "main peat" of Mr SpuiTell), which is
described as consisting mainly of Phragmites and
Sparganiiim, with layers of moss and fronds of fern.
The other plants observed in this peat were the elder,
white-birch, alder and oak. Associated with them
were found several species of freshwater snails and
a few land forms ; but the only animal or plant
showing any trace of the influence of salt water was
Hydrohia ventrosa, a shell that requires slightly
brackish water.

The main peat rests on another bed of estuarine
silt (7 and 8), which seems to vary considerably in
thickness, from 5 to 12 feet. It is not quite clear
from the descriptions whether the "thin woody peat"
of Mr Whitiiker and the "sand with decayed wood"

II] THE THAMES VALLEY 17

(9) of the engineer represent a true growth in place,
like the main peat ; it is somewhat irregular and
tends to abut against banks of sand (9*) rising
from below. In one of these banks, according to
Mr Spurrell, the human skeleton was found.

The contents of the sand (other than the skeleton)
included Bythinia and Suceinea ; and as Mr Spur-
rell calls it a " river deposit," it apparently did not
yield estuarine shells, like the silts above. The sub-
angular flint gravel (10) below has all the appearance
of a river gravel ; it may be from 10 to 20 feet thick,
and rests on chalk only reached in borings.

The floor of chalk beneath these alluvial deposits
lies about 60 or 70 feet below the Ordnance datum in
the neighbourhood of Tilbury and Gravesend, and
in the middle of the ancient channel of the Thames
it may be 10 feet lower ; but there is no evidence of
a greater depth than this. We may take it there-
fore that here the Thames once cut a channel about
60 feet below its modern bed. We cannot say, how-
ever, from this evidence alone that the sea-level then
was only 60 feet below Ordnance datum, for it is
obvious that it may have been considerably lower.
If, as we believe, the southern part of the North Sea
was then a wide marsh, the Thames may have fol-
lowed a winding course of many miles before reaching
the sea, then probably far away, in the latitude of the
Dogger Bank. This must be borne in mind : we

R. 2

18 SUBMERGED FORESTS [ch.

know the minimum extent of the change of level ;
but its full amount has to be ascertained from other
localities.

This difficulty has seemed of far greater importance
than it really is, and some geologists have suggested
that at this period of maximum elevation, England
stood several hundred feet higher above the sea than
it does now. I doubt if such can have been the case.
Granting that the sea may have been some 300 miles
away from Tilbury, measured along the course of the
winding river, this 300 miles would need a very small
fall per mile, probably not more than an inch or two.
The Thames was rapidly growing in volume, from the
access of tributaries, and was therefore flowing in a
deeper and wider channel, which was cut through
soft alluvial strata; it therefore required less and less
fall per mile. Long before it reached the Dogger it
probably flowed into the Rhine, then containing an
enormous volume of water and draining twice its
present catclunent area.

The clean gravel and sand which occupy the lower
part of the ancient channel at Tilbury require to be
more closely examined, for it is not clear that they
are, as supposed, of fluviatile origin ; they may quite
well be estuarine. In the sand Mr Spurrell found
the freshwater shells Bytkinia and Sncciuea, and in
it was also found the human skeleton described by
Owen ; but, accoi'ding to Mr Spurrell, on the surface

Ill] THE EAST COAST 19

of this sand lay a few stray valves of the estuarine
ScroUcularia and of TelUna. The bottom deposits
were probably laid down in a tidal river ; but whether
within the influence of the salt water is doubtful.

As far as the Tilbury evidence goes it suggests a
maximum elevation of the land of about 80 feet above
its present level ; but we will return to this question
when we have dealt with the other rivers flowing more
directly into deep sea. The animals and plants found
at Tilbury were all living species.

It is unnecessary here to discuss more fully the
submerged forests seen in dock and other excava-
tions in the Thames flats, for they occupy a good
many pages in the Geology of London published by
the Geological Survey. Even 250 years ago, the hazel
trees were noticed by the inquisitive Pepys during
one of his official visits to the dockyards, and later
writers are full of remarks on the ancient yew trees
and oaks found well below the sea-level. Most of
these early accounts are, however, of little scientific
value.

CHAPTER HI

THE EAST COAST

It is not our purpose to describe in detail the
many exposures of submerged land-surfaces which
have been seen on the shores of the North Sea. This

2—2

20 SUBMERGED FORESTS [ch.

would serve no useful purpose and would be merely
tedious. We need only say that the floor of Eocene or
Cretaceous strata on which these ancient subaerial
deposits rest is constantly found at depths of 50 or
60 feet below the level of the existing salt-marsh.
But where, as in the estuary of the Thames and
Humber, an older channel underlies a modern
channel, the floor sinks about 30 feet lower. From
present marsh-level to ancient marsh-level is about
60 feet ; from present river-bottom to old river-
bottom is also about 60 feet. This, therefore, is the
extent of the former elevation, unless we can prove
that the sea was then so far away that the river once
had many miles to flow before reaching it. This is
the point we have now to consider as we trace the
submerged forests northward and towards the deeper
seas.

Before we leave the southern part of the North
Sea basin it will be well to draw attention to a few
of the half-tide exposures which for one reason or
another may tend to mislead the observer. The mere
occurrence of roots below tide marks is not sufficient
to prove that the land-surfaces seen are all of one date.

Not far from Tilbury is found the well-known
geological hunting ground of Grays, where the brick-
yards have yielded numerous extinct mammalia and
several land and freshwater shells now extinct in
Britain. These deposits lie in an old channel of the

Ill] THE EAST COAST 21

Thames, cut to below mean -tide level, but here not
coinciding exactly in position either with the channel
of the existing river, or with the channel in which
the submerged forests lie.

It is fortunate that the channels do not coincide,
for this enables us to distinguish the more ancient
deposits, A glance at a geological map shows, how-
ever, that they must coincide elsewhere, and where
the Thames has re-occupied its old channel it is clear
that the destruction of the earlier deposits may have
led to a mixture of fossils and implements belong-
ing to three diiferent dates. Mammoth teeth and
Palaeolithic implements, Irish elk and polished stone
implements, may all be dredged up in the modern
riv6r gravel, associated with bits of iron chain, old
shoes, and pottery. Such a mixture does actually
occur in the Thames estuary, and it makes us hesitate
to accept the teeth of mammoth which were dredged
in the Thames as really belonging to so late a period
as that of the submerged forests.

At Clacton a similar difiiculty is met with, for
there again an ancient channel contains alternating
estuarine and freshwater deposits with layers of peat,
and is full of bones belonging to rhinoceros, hippo-
potamus, elephant and other extinct mammalia. Of
course the peat-beds in this channel are just as much
entitled to the name " submerged forest " as the more
modern deposits to which recent usage restricts it.

22 SUBMERGED FORESTS [ch.

They belong, however, to another and more ancient
chapter of the geological record than that with which
we are now dealing. I do not say a less interesting
one, for they are of the greatest importance when we
study the times when Palaeolithic man flourished ; but
at present we have as much as we can do to under-
stand the later deposits and to realize the great
changes to which they point. We must not turn
aside for everything of interest that we come across
in this study ; these earlier strata are worthy of a
book to themselves.

As we travel northward along the coast, again and
again we meet with evidence of a submerged nearly
level platform, "basal plane," or ancient "plane of
marine denudation," lying about 50 feet below the
sea. We find it at Langer Fort, which lies opposite
to Harwich on a spit of sand and shingle stretching
across Harwich Harbour. Here the floor of London
Clay was met with in a boring at 54 feet beloAv the
surface.

The Suflblk coast north of Southwold yields yet
another complication, for between Southwold and
Shcrringham in Norfolk there appears at the sea-
level a land-surface considerably more ancient than
anything we have yet been dealing with. This is
the so-called " Cromer Forest-bed," which co!isists of
alternating freshwater and estuarine beds, with
ancient land-surfaces and masses of peat. It contains

Ill] THE EAST COAST 23

iiuiiierous extinct inainmals, maiuly of species older
than and diiferent from those of Clacton and Grays.

The mammalian remains differentiate these de-
posits at once ; but if no determinable mammals are
found, the crushing of the bones and the greater
compression and alteration of tlie peaty beds serves
to distinguish them, for this Forest-bed dates back to
Pliocene times, passes under a considerable thickness
of glacial beds, and has been over-ridden by the ice-
sheet during the Glacial epoch.

The Cromer Forest-bed has been exposed particu-
larly well of late years at Kessingland, near Lowestoft,
where the sea has encroached greatly. It is well
worth while to make a comparative study of this
deposit, of the Grays and Clacton Ci/reHa-hed, of the
submerged forests of the Thames docks, and of the
strata now being formed in and around the Norfolk
Broads. By such a comparison we can trace the effects
of similar conditions occurring again and again. The
fauna and flora slowly change, species come and go,
man appears and races change: though the same
physical conditions may recur life ever changes.

The Norfolk Broads, just referred to, deserve
study from another point of view : their origin is
directly connected with the submergence which forms
the theme of this book. These broads are shallow
lakes, always occupying part of the widest alluvial
flats which border the rivers ; but they are usually

24 SUBMERGED FORESTS [ch.

out of the direct course of the present river ; they
therefore receive little of the sediment brought down
in flood-time. On the other hand they are steadily
being filled up with growing vegetation and turned
into peat mosses.

The origin of these shallow^ freshwater lakes, which
form a characteristic feature in the scenery of East
Anglia, has been much debated ; but with the know-
ledge obtained from a study of the submerged forests
the explanation is perfectly simple. During this
period of slow submergence each of the shallow
valleys in which the broads now lie was turned into
a wide and deep navigable estuary, which extended
inland for many miles. When the subsidence stopped
the sea and tides soon formed bars and sand-banks
at the mouths of the estuaries, and lateral tributaries
pushed their deltas across. The Norfolk rivers, being
small and sluggish, were driven to one side, and could
neither cut away the sand-banks nor fill up with
sediment such wide expanses. These estuaries there-
fore were silted up with tidal mud and turned into
irregular chains of lakes, sepai"ated by irregular
bars and sand-banks. The lakes, instead of be-
coming rapidly obliterated and filled up by deltas
which crept gradually seaward, remained as fresh-
water broads ; for as soon as a bank became hiuh
enough for the growth of reeds and sedges the river
mud was strained out and only nearly clean water

Ill] THE EAST COAST 25

reached the lagoon behind. Thus a depression once
left, provided it was out of the direct course of the
river, tended to remain as a freshwater lake until
vegetable growth could fill it, and the river mud was
spread out over the salt-marshes or went to raise
the sand-banks till they became alluvial flats, and
thus still more thoroughly isolated the broad.

A few centuries will see the disappearance of the
last of the broads, which have silted up to an
enormous extent within historic times ; but the fact
that so many of these broads still exist may be taken
as clear evidence of the recent date of the depression
which led to their formation.

When we look at ancient records, and notice the
rapidity with which the broads and navigable estuaries
are becoming obliterated, we cannot help wondering
whether the measure of this silting up may not give
us the date of the last change of sea-level. It should
do so if we could obtain accurate measurements of
the amount of sediment deposited annually, of the
rate at which the sea is now washing it in, and of the
rate at which the rivers are bringing it down. All
these factors, however, are uncertain, and it is
particularly difficult to ascertain the part played by
the nmddy tidal stream which flows in after storms
and spreads far and wide over the marsh.

Though all the factors are so uncertain, we can
form some idea of the date of the submergence.

26 SUBMERGED FORESTS [CH.

Many years ago I made a series of calculations,
founded on the silting up of our east coast estuaries,
the growth of the shingle-spits, and the accumulation
of sand-dunes. The results were only roughly con-
cordant, but they seemed to show that the subsidence
stopped about 2500 years ago and was probably still
in progress at a date 500 years earlier. This ques-
tion of dates will be again referred to in a later
chapter.

Before leaving the Broad district we must refer
to a boring made at Yarmouth, which, according to
Prof. Prestwich, showed that the recent estuarine
deposits are there 120 feet thick, and consequently
that the ancient valley was far deeper than any
recorded in the foregoing pages. There is no doubt,
however, that this interpretation is founded on a
mistake, for other borings at Yarmouth, Lowestoft,
and Beccles came to muddy sands and clays belonging
to the upper part of the Crag, now known to thicken
gi-eatly eastward. The recent deposits descend only
to a depth of about 50 feet at Yarmouth, and consist
of sand and shingle ; the beds below contain Pliocene
mollusca. This emendation is also borne out by the
entirely different character of the recent estuarine
deposits at Potter Heigham, where we again find a
submerged forest at about 50 feet below the marsh-
level. The section recorded by Mr Blake is as
follows : —

Ill] THE EAST COAST 27

feet

Bluish-grey loam 24

Grey silty sand ... ... ... ... £, to 2

Stiff bluish-grey loam, clay, and silt full of

cockles, &c. ... ... .. ... 13

Black peat, hard, and much compressed ... 17

White and buff sand 2

58

It will be noticed that here only one peat bed was
found, and was at the usual depth of the lowest sub-
merged forest. Possibly the wiiite sand below was
the bleached top of the Crag ; but this point was not
cleared up.

If we resume our journey northward along the
Norfolk coast we come to the well-know n locality of
Eccles, where the old church tower described and
figured by Lyell in his Prhiciples of Geology long
stood on the foreshore, washed by every spring tide.
The position of this church formed a striking illustra-
tion of the protection aftbrded by a chain of sand-
dunes. ' The church was originally built on the
marshes inside these dunes, at a level just below that
of high-water spring tides. But as the dunes were
driven inland they gradually overwhelmed the church,
till only the top of its tower appeared above the sand.
In this state it was pictured by Lyell in the year
1H39. Later on (in 186-2) it was again sketched by
the Rev. S. W. King, and stood on the seaward side
of the dune and almost free from sand. For a series

28 SUBMERGED FORESTS [ch.

of years, from 1877 onward, I watched the advance of
the sea, and as the church tower was more and more
often reached by the tides, its foundations were laid
bare and attacked by the waves, till at last the tower
fell.

Not only were the foundations of Eccles church
exposed on the foreshore, but an old road across the
marshes also appeared on the seaward side of the
dunes, giving a still more exact idea of the former
great influence of the chain of dunes in damping the
oscillations of the tidal wave. The tide outside now
rises and falls some 12 or 15 feet; on the marsh
within its influence is only felt under exceptional
circumstances. A road across the marsh at a level
four or five feet below high-water, as this one stood,
would still be passable, except during unusual floods.

Eccles Church is an excellent example of the way
in which an ancient land-surface may now be found
below the level of high-water, and yet no subsidence
of the land has taken place. But this coast can give
even more curious examples. It does not need a sand-
dune to deaden the rise and fall of the tides ; even
a submerged bank will have much the same eft'ect.
Extensive submerged sand-banks extend parallel
with the coast, protecting the anchorage known as
Yarmouth Roads. These banks rise so nearly to the
surface of the sea that not only do they protect the
town and anchorage against tlie waves, they deaden

Ill] THE EAST COAST 29

tlie tidal oscillation to such an extent that its range
is much greater outside the bank than within.

If these submerged outer banks were to be swept
away by some change in the set of the currents, large
areas now cultivated and inhabited v/ould be flooded
by salt water at every spring tide, and the turf of the
meadows would be covered by a layer of marine silt,
such as we see alternating with the submerged forests
in the docks of the Thames. Such alternations, if
thin, do not necessarily prove a change in the level
of the sea ; they may only point to the alternate
accumulation and removal of sand-banks in a distant
part of the estuary.

The Norfolk coast trends westward soon after
leaving Cromer, and where the cliff seems to pass
inland at \Yeybourn we enter an ancient valley, one
side of which has been entirely cut away by the sea,
except for a few relics of the further bank, now
included in the shingle beach which runs out to sea
nearly parallel with the coast and protects Blakeney
Harbour. Here again we find that in the bottom of
the valley there must be a submerged forest, for
slabs of peat are often thrown up at Weybourn, and
by the use of a grapnel the peat was found in place
ofi* Weybourn at a depth of several fathoms.

When the coast turns southward again, and the
wide bay of the Wash is entered, we find an exten-
sive development of submerged land-surfaces and peat

30 SUBMERGED FORESTS* [ch.

beds, extending over gi-eat part of the Fenland. In
fact the whole Fenland and Wash was once a slightly
undulating plain, cut into by numerous shalloAv open
valleys. The etlect of the submergence of this area
has been to cause the greater part of it to silt up to
a uniform level, through the accumulation of warp
and growth of peat ; so that now the Fenland has
become a dead level, out of which a few low hills rise
abruptly. The islands of the Fenland, such as those
on which Ely and IMarch are built, are merely almost
submerged hill-tops ; they were not isolated by marine
action.

It is obvious that a wide sheltered bay of this sort
forms an ideal area in which to study the gradual
filling up and obliteration of the valleys, as the land
sank ; and it may enable us to learn the maximum
amount of the change of sea-level. The Fenland
unfortunately does not contain very deep dock
excavations, and we have only various shallower
engineering works to depend on, though numerous
borings reach the old floor.

A preliminary difficulty, however, meets us in the
study of the Fen deposits ; it is the same difficulty
that we have already i-eferred to when describing
Clacton and Grays, and we shall meet with it again.
In certain parts of the Fenland, particularly about
March and Chatteris, a sheet of shoal-water marine
gravelly sand caps some of the low hills, which rise a

Ill] THE EAST COAST 31

few feet above the fen-level. The gravel for long was
taken to be the same bed that passes under the
marshes. Later work showed however that these
gravels, with their sub-arctic marine fauna and con-
taining also Corbicula flmninalis, were of much
earlier date than the true fen-deposits. Just as we
saw happen in the Thames Valley, a wide plain and
estuary existed long before the deeper channels
containing the submerged forests were cut ; and the
deposits of this older estuary and its tributaries are
still to be found in patches here and there. Some-
times, as at March, they cap hills a few feet above
the fen-level ; but as often they fill channels not
quite coinciding with the later channels; just as they
do at Grays. Or two deposits of quite different date
may lie side by side, as they do in the Nar Valley, or
at Clacton, or on the Sussex coast.

The true fen-deposits were carefully examined by
Messrs. Marshall, Fisher, and Skertchly, as far as
the shallow sections would allow, and the following-
account is mainly condensed from that given by
Mr Skertchly in his Geologj/ of the Fcnland.

During the excavation of certain deep dykes for
the purpose of draining the fens there was discovered
at a depth of about 10 feet below the surface a forest
of oaks, with their roots imbedded in the underlying
Kimmeridge C-Iay. The trunks were broken off at a
height of al)ont three feet. Some of the fallen trees

32 SUBMERGED FORESTS [ch.

were of fine proportion, measuring three feet in
diameter, quite straight and seldom forked. At an
average height of two feet above this " forest No. 1 "
the remains of another were found (in the peat)
consisting of oaks and yews. Three feet above
" forest No. 2 " lay the remains of another, in which
the trees are all Scotch firs, some of which were three
feet in diameter. Above this and near to the surface
was seen a still newer forest of small firs. The peat
close to the surface contains remains of sallow and
alder, and was formed with the sea at its present
level.

It will be noticed that the greatest depth at which
these rooted trees were found Avas only about ten feet
below the sea-level. At this high level we must
expect to find that the growth of the peat was
practically continuous, and that the different sub-
merged forests run together. In adjoining depressions
the difterent forests would occur at lower levels and
would be separated by beds of marine silt. It does
not follow from the position that a low-level sub-
merged land-surface is older than one at a higher
elevation, for above the present sea-level all these
stages are represented by a few inches of soil, on
which forest after forest has grown and decayed.
Anyone who has collected antiquities on fields knows
what a curious jumble of Palaeolithic, Neolithic,
bronze age, Roman, mediaeval and recent things may

iTi] THE EAST COAST 33

be found mixed in these few inches of soil, or may be
thrown up by an uprooted tree. The great advantage
of studying the deeply submerged forests is that in
them the successive stages are separated and isolated,
instead of being mingled in so confusing a fashion.

For further information as to the more deeply
submerged land-surfaces we may turn to the numerous
records of borings made in the Fenland and collected
by the Geological Survey. These show that the
thickness of the fen-deposits varies considerably from
place to place, that the floor below undulates and is
by no means so flat as the surface of the fen above.
Most of these borings, however, were not continued
through the gravels which lie at the base of the
deposit, and thus we can only be certain of the total
depth to the Jurassic clay or boulder clay in a few
places. The maximum thickness of the fen-beds yet
penetrated is less than 60 feet, and a submerged
forest was found at Eaubrink at about 40 feet. It
is possible however that none of these scattered
borings has happened to hit upon one of the buried
river-channels, which formerly wandered throughfthis
clayey lowland ; if one were found it would probably
show that the alluvial deposits are somewhat thicker
than these measurements, and that they descend to
a depth about equal to that reached in the valleys of
the Thames or Humber.

It is useless to discuss in more detail the lower

R. 3

34 SUBMERGED FORESTS [ch.

submerged forests of the Fenland, for we cannot get
at them to examine them properly. They have been
as effectually overwhelmed and hidden as the remains
of King John's baggage train, which has never been
seen again since it wandered off the flooded causeway
during the disastrous spring-tide of October 11, 1216,
and sank into the soft clay and quicksands.

The higher submerged forests of the Fenland are
however of great interest, and as already pointed out
they have been exposed to view in cutting the fen
dykes, especially near Ely. Perhaps a closer study
of these might enable us to arrive at some idea of
the time taken for the gro^Hh of a series of forests
of this sort, and for the accompanying mass of peat.
The variations in the flora also need more exact
analysis before we can say what they betoken. The
oak-forest at the bottom is what we should expect
on a clay soil ; but the reason for the succession of
trees above is not obvious. It need not necessarily
point to climatic change, though it may do so ; but
it certainly looks as if the peaty bogs were alternately
wetter and drier, so that sometimes moss gi*ew, and
sometimes fir-trees. Neither need this change imply
an up-and-down movement of the land, though it
may be due to such a cause.

Subsidence would destroy the oaks and allow a
peat-moss to form ; but if the subsidence were inter-
mittent the moss would increase in thickness, become

Ill] THE EAST COAST 36

more compact, and its surface rise, till it was dry
enough for pines. Another subsidence would cause
spongy peat again to spread and kill the pine, and
so on. Intermittent subsidence seems sufficient to
account for all the changes of vegetation we have
yet noticed in connexion with these submerged land-
surfaces.

Of the fauna of the fen-silts and peats it is very
difficult to give any satisfactory account. If we put
aside the March and Chatteris marine gravels with
Corhicida fluminalis, and the Nar Valley Clay with
its northern marine mollusca as being of older date ;
and if we also reject the marginal gravels with
hippopotamus and mammoth as being more ancient,
there only remain a few mammals such as the beaver,
wolf, wild boar, and certain cetacea, which we can be
sure came out of the true fen-deposits. Implements
made by man have only been found in the higher
layers, and there seems to be no record in this area
of a stone implement found below a submerged
forest.

Submerged forests of the ordinary type are often
to be seen between tide-marks on the flat shores of
Lincolnshire ; but as they still await proper study
they need not here detain us, and we will pass on
to the next large indentation of the coast-line, the
estuary of the Humber.

Here, owing to the excavation of extensive docks,

3—2

36 SUBMERGED FORESTS [ch.

and to a series of trial borings for a tunnel beneath
the Humbcr, the structure of the valley has been
clearly laid open. It is much the same as that of the
Thames ; but as we are in a glaciated area we find,
as in the Fenland, that much of the erosion had taken
place before or during the Glacial Epoch, for boulder
clay occupies part of the valley.

Boulder clay or till not only occupies part of the
valley, it descends far below the present river bottom
and even below the lowest submerged forest. This
we find always to be the case in the glaciated parts

Humbcr

McGlitf-.ic
Channel

m

^

^^..H-gy^Tiah w«t^ef

IKTffSk

^;^,-^!jjiw_jaatfif

■"■"liillilHI^

-■— -^n^

Ch^„

C^"-'

■ '' kiiiirneridge

Clay

- — -

Fig. 3.

of Britain ; but whether the deep trenching is due to
the ploughing out of a trough by a tongue of the ice-
sheet, to sub-glacial streams below sea-level, or to
erosion by a true sub-aerial river is still a dou})tful
point. However, this question must not detain us ;
we are not now dealing with elevations and depres-
sions of so ancient a date, and must confine our
attention to post-glacial movements.

The section shown in fig. 3 will explain better
than any words the structure of the Humber Valley.

Ill] THE EAST COAST 37

It is drawn to scale from the engineer's section, and
shows at a glance the three channels. The deepest
and widest channel is that occupied by glacial
deposits ; an intermediate channel (shown in black)
is occupied by silt and submerged forests ; and a
shallower channel is occupied by the present Humber
and its alluvium. One interesting point, however,
this section does not happen to illustrate. Somewhat
lower down the Humber we come to gravels and silts
full of sub-arctic marine mollusca and Corbicula
jltvminalis, exactly as in regions further south, and
presumably of the same age as the deposits we have
already mentioned as found at March in the F'enland
and at Grays in Essex. The exact relation of these
Corbicula-heds to tlie deep channel filled with glacial
drift, below the marshes of the present Humber, is
still somewhat uncertain, but the marine beds clearly
rest on boulder clay, and seem also to be overlain by
another glacial deposit.

The section leaves no doubt that in post-glacial
times the Humber cut a channel about 60 feet below
its present bed, or to just the same deptli as did the
Thames. This may })ossibly be an accidental coinci-
dence ; but it is very suggestive that both these rivers
should have cut their beds to the same depth. Such
coincidences suggest that we are dealing with a period
when each of our great rivers was able to cut to a
definite base-level, below which it could not go. This

38 SUBMERGED FORESTS • [ch.

base-level must either have been the sea, or some
vast alluvial plain then occupying the bed of the
North Sea. In either case the plain must then have
been fully 60 feet lower than the present sea-level.
Not only did the ancient Humber cut to the same
depth as the ancient Thames, but in each area the
ancient river was flanked by a wide alluvial flat which
now lies from 40 to 60 feet below the modern marsh
level.

The flat coast of Holderness, which stretches from
the Humber northward to Flamborough Head, shows
also occasional submerged forests ; but the want of
excavations beneath the sea-level makes it impossible
to say much about them. North of Flamborough
Head it seems as though depression gave place to
elevation, and when we pass into Scotland tlie Neo-
lithic deposits seem to be raised beaches instead of
submerged forests. We need not therefore devote
more time to a consideration of the details connected
with the submerged land-surfaces which border the
lands facing the North Sea. They evidently once
formed i)art of a wide alluvial flat stretching seaward
and running up all our larger valleys. We must
now consider how far seaward this plain formerly
extended.

Here, fortunately, we meet with a most surprising
piece of evidence, which adds enormously to the im-
portance of this plain, and shows that the submergence

IV] THE DOGGER BANK 39

is no local phenomenon, but a widespread movement
of depression which must greatly have altered the
physical geography of north-western Europe during
times within the memory of man. This evidence
deserves a separate chapter.

CHAPTER IV

THE DOGGER BANK

For the last 50 years it has been known to geolo-
gists that the bed of the North Sea yields numerous
bones of large land animals, belonging in gi-eat part
to extinct species. These were first obtained by
oyster-dredgers, and later by trawlers. Fortunately
a good collection of them was secured by the British
Museum, where it has been carefully studied by
William Davies. The bones came from two localities.
One of them, close to the Norfolk coast off Happis-
burgh, yielded mainly teeth of Elephas meridionalis,
and its fossils were evidently derived from the Pliocene
Cromer Forest-bed, which in that neighbourhood is
rapidly being destroyed by the sea. This need not
now detain us.

The other locality is far more extraordinary. In
the middle of the North Sea lies the extensive shoal
known as the Dogger Bank, about GO or 70 miles

Ot^iSl

Fig. 4. — Showing approximate CoaBt-line at tLe period of
the lowest Submerged Forest.

CH. IV] THE DOGGER BANK 41

from tlie nearest laud. This shoal forms a wide
irregular plateau having an area nearly as big as
Denmark. Over it for the most part the sea has
a depth of only 50 or 60 feet; all round its edge
it slopes somewhat abruptly into deeper water, about
150 feet in the south, east, and west, but much deeper
on the north. This peculiar bank has been explained
as an eastward submerged continuation of the Oolite
escarpment of Yorkshire; or, alternatively, as a mere
shoal accumulated through the effects of some tidal
eddy ; but neither of these explanations will hold, for
Oolitic rocks do not occur there, and the bank has a
core quite unlike the sand of the Xorth Sea.

AVhen trawlers first visited the Dogger Bank its
surface seems to have been strewn with large bones
of land animals and loose masses of peat, known to
the fishermen as *'moorlog," and there were also many
erratic blocks in the neighbourhood. As all this
refuse did much damage to the trawls, and bruised
the fish, the erratics and bones were thrown into
deeper water, and the large cakes of moorlog were
broken in pieces. A few of the erratics and some of
the bones were however brought to Yarmouth as
curiosities. Now the whole surface of the Dogger
Bank has been gone over again and again b}^ the
trawlers, and very few of the fossil bones are found ;
unfortunately no record seems to have been kept as
to the exact place where these bones were trawled.

42 SUBMERGED FORESTS [oh.

The species found were : —

Ursus (bear) Bison priscus (bison)

Canis lupus (wolf) Equus caballus (horse)

Hyaena spelaea (hyaena) Ehiuoceros tiohorhinus (woolly
Cerviis megaceros (Irish elk) rhinoceros)

,, tarandus (reindeer) Elephas primigenius (mammoth)

,, elaphus (red-deer) Castor fiber (beaver)

,, a fourth species Trichechus rosmarus (walrus)
Bos primigenius (wild ox)

Though mammalian bones are now so seldom
found, whenever the sand-banks shift slightly, as they
tend to do under the influence of tides and currents,
the edges of the submerged plateau are laid bare,
exposing submarine ledges of moorlog, which still
yield a continuous supply of this material, Messrs.
Whitehead and Goodchild have recently published an
excellent account of it, having obtained from the
trawlers numerous slabs of the peculiar peaty dejiosit,
with particulars as to the latitude and longitude in
which the specimens were dredged. Mrs Reid and T
have to thank the authors for an opportunity of
examining samples of the material, which has yielded
most interesting evidence as to the phj'sical history,
botany, and climatic conditions of this sunken land.
The following account is mainly taken from their
paper and our appendix to it.

We are still without information as to the exact
positions of the submarine ledges and clifls of peat
from which the masses have been torn; but there

IV] THE DOGGER BANK 43

seems little doubt that some of tliem were actually
torn off by the trawl. One block sent to me Avas full
of recently dead half-grown Pholas parva, all of one
age, and must evidently have been torn off the solid
ledge. Pholas never makes its home in loose blocks.
We unfortunately know very little about the natural
history of the boring mollusca and their length of life.
If, as I think, this species takes two years to reach
full growth, then it is evident that the ledge of moor-
log full of half-grown specimens must have been
exposed to the sea continuously for one year, but not
for longer. It ought also perhaps to tell us the depth
of water from which the mass was torn ; but nothing
is known as to the depth to which Pholas may extend
— it has tlie reputation of occurring between tide-
marks or just below, but it may extend downwards
wherever there is a submarine cliff.

Though we are still unable to locate exactly these
submarine ledges or fix their depth below the sea, the
blocks of moorlog are so widely distributed around
the Dogger Bank, and have been dredged in such
large masses, that it seems clear that a "submerged
forest" forms part of tlie core of the bank. As nothing
else approaching to a solid stratum appears to be
dredged over this shoal, we may assume that the
moorlog forms a sort of cap or cornice at a depth of
about 10 fathoms, overlying loose sandy strata, and
perhaps boulder clay, which extend downward to

44 SUBMERGED FORESTS [ch.

another 10 fathoms, or 120 feet altogether. Unfor-
tunately we cannot say from wliat deposit the large
bones of extinct animals were washed ; they may come
from the sands below the moorlog, but it is quite as
probable that the Pleistocene deposits formed islands
in the ancient fen — as they do now in East Anglia,
Holderness, and Holland.

More than one svibmerged forest may be present
on the Dogger Bank. The masses of moorlog are
usually dredged on the slopes at a depth of 22 or 23
fathoms ; but at the south-west end it occurs on the top
as well as on the slope, the sea-bottom on which the
moorlog is found consisting of fine grey sand, probably
an estuarine silt connected with the submerged forest,
for the North Sea sand is commonly coarse and gritty.

With regard to the moorlog itself and its contents,
it is possible that some of the mammals in the list,
such as the reindeer, beaver, and walrus, may belong
to this upper deposit; but we have no means of dis-
tinguishing them, as the bones were all found loose
and free from tlie matrix. The insects and plants
were all obtained from slabs of this peat.

The dredged cakes of peat handed to us for ex-
amination came from different parts of the Bank ; but
tliey were all very similar in character, and sliowed
only the sliglit ditt'erences found in different parts of
the same fen. The bed is essentially a fen-deposit of
piu'ely organic origin, witli little trace of inorganic

ivj THE DOGGER BANK 45

mud. It is fissile and very hard'wlieii dry, and in it
are scattered a certain number of fairly well-preserved
seeds, principally belonging to the bog-bean. Other
recognis^able plant-remains are not abundant. They
consist of rare willow-leaves, fragments of birch- wood
and bark, pieces of the scalariform tissue and sporangia
of a fern, and moss, and, curiously enough, of groups
of stamens of willow-herb with Avell-preserved pollen-
grains, though the whole of the rest of the plant to
whicii they belonged had decayed.

The material is exceptionally tough, and is very
difficult to disintegrate. In order to remove the
structureless humus which composed the greater part
of the peat, we found it necessary to break it into
thin flakes and boil it in a strong soda solution for
three or four days. Afterwards the material was
passed through a sieve, the fine flocculent parts being
washed away by a stream of water, the undecomposed
plant remains being left behind in a state for examina-
tion. These remains were mixed with a large amount
of shreds of cuticle, etc., but recognisable leaves were
not found in the washed material.

The general result of our examination is to suggest
that the deposit comes from the middle of some vast
fen, so far from rising land that all terrigenous material
has been strained out of the peaty water. The vege-
tation, as far as we have yet seen, consists exclusively
of swamp species, with no admixture of hard-seeded

46 SUBMERGED FORESTS [cH.

edible fniits, usually so widely distributed by birds,
and no wind-borne composites. The sea Mas probably
some distance away, as there is little sign of brackish-
water plants, or even of plants which usually occur
within reach of an occasional tide ; one piece however
yielded seeds of Bnppta. The climate to which
the plants point may be described as northei-n. The
white-birch, sallow and hazel were the only trees;
the alder is absent. All the plants have a high
northern range, and one, the dwarf Arctic-birch, is
never found at sea-level in latitudes as far south as
the Dogger Bank (except very rarely in the Baltic
provinces of Germany).

The plants already found are :—

Ranunculus Lingua Betula alba
Castalia alba „ nana

Cochlearia sp. Corylus Avellana

Lychnis Flos-cuculi Salix repens
Arenaria trinervia ,, aurita

Spiraea Ulmaria Sparganium simplex

Rubus fruticosus Alisma Plantago

Epilobiuni sp. Potamogeton natans

Galium sp. Ruppia rostellata

Valeriana officinalis Scirpus sp.

Menyantnes trifoliata Carex sp.

Lycopus europaeus Phragmites communis
Atriplex patula

Among the nine species of beetle determined by
Mr G. C. Champion it is noticeable that two belong
to sandy places. This suggests that the fen may ha^'e

IV] THE DOGGER BANK 47

had its seaward edge protected by a belt of sand-dunes,
just as the coast of Holland is at the present day.

This submerged forest in the middle of the North
Sea has been described fully, for it raises a host of
interesting questions, that require much more research
before we can answer them. A sunken land-surface
60 feet and more below tlie sea at high-tide corresponds
very closely with the lowest of the submerged forests
met with in our dock-excavations. But if another bed
of peat occurs at a depth of 130 or 140 feet at the
Dogger Bank, this would be far below the level of any
recently sunk land-surface yet recognised in Britain.
Also, if the slabs of very modern-looking peat, contain-
ing only plants and insects still living in Britain, come
from such a depth, out of what older deposit can the
Pleistocene mammals, such as elephant, rhinoceros,
and hyaena, have been washed?

These questions cannot be answered conclusively
without scientific dredging, to fix the exact positions
and depths of the outcrops of moorlog. When we
remember also that beneath a submerged forest at
about the depth of the Dogger Bank there was found
at Tilbury, in tlie Thames Valley, a human skeleton ;
and that both human remains and stone implements
have been discovered in similar deposits elsewhere, we
can point to the Dogger Bank as an excellent field
for scientific exploration.

The Dogger Bank once formed the northern edge

48 SUBMERGED FORESTS [ch.

of a great alluvial plain, occup3Mng- what is now the
southern half of the North Sea, and stretching across
to Holland and Denmark. If we go beyond the
Dogger Bank and seek for answers to these questions
on the further shore, we find moorlog washed up
abundantly on the coasts of both Holland and Denmark,
and it has evidently been torn off submerged ledges
like those of the Bank. Xumerous borings in Holland
give us still further information, for they show that
beneath the wide alluvial plain, which lies close to the
level of the sea, there exists a considerable thickness
of modern strata. At Amsterdam, for instance, two
beds of i)eat are met with well below the sea-level, the
upper occurring at about the level of low-tide, the
lower at a depth of about 50 or 00 feet below mean-
tide. That is to say, the lowest submerged land-
surface is found in Holland at just about the same
depth as it occurs in England, and probably on the
Dogger Bank also.

Below this submerged land-surface at Amsterdam
are found marine clays and sands, which seem to
show that the lowest " continental deposit," as it is
called by Dutch geologists, spread seaward over the
silted-up bed of the North Sea ; but no buried land-
surfaces have yet been found below' the (lO-foot level
anywhere in Holland.

This appearance of two distinct and thick peat-
))eds, underlain, separated, and overlaid by marine

IV] THE DOGGEH BANK 49

deposits, seems to characterise great part of the
Dutch plain. It points to a long period of sub-
sidence, broken by two intervals of stationary sea-
level, when peat-mosses flourished and spread far and
wide over the flat, interspersed with shallow lakes,
like the Norfolk broads.

The enclosed and almost tideless Baltic apparently
tells the same story, for at Rostock at its southern
end, a submerged peat-bed has been met with at a
depth of 46 feet.

On passing northward into Scandinavia Ave enter
an area in which, as in Scotland, recent changes in
sea-level have been complicated by tilting, so that
ancient beach-lines no longer correspond in elevation
at diiferent places. The deformation has been so
great that it is impossible to trace the submerged
forests ; they may be represented in the north by
the raised beaches, which in Norway and Sweden, as
in Scotland and the north of Ireland, seem to belong
to a far more recent period than the raised beaches
of the south of England. It seems useless to attempt
to continue our researches on submerged forests fur-
ther in this direction, especially as during the latest
stages, when we know England was sinking, Gothland
appears to have been slowly rising. Those who wish
to learn about the changes that took place in the
south of Sweden should refer to the recent mono-
graph by Dr Munthe.

R. 4

50 SUBMERGED FORESTS [ch.

CHAPTER V

THE IRISH SEA AND THE BRISTOL CHANNEL

On the west coast of Scotland, as on the east,
the succession of events seems to have been quite
different from that which can be proved further
soutli. It looks as though we must seek for equi-
valents of our submerged forests in certain very
modern looking raised beaches and estuarine de-
posits, such as those of the Clyde. Even when we
move southward to the Isle of Man deeply submerged
post-glacial land-surfaces appear to be unknown,
though there is evidence of a slight sinking, and
roots of trees are found a few feet below the sea-
level. In the Isle of Man we still come across the
modern-looking raised beaches so prevalent in Scot-
land though unknown in England.

The Lancashire and Cheshire coasts, with their
numerous deep estuaries and extensive flats, are
noted, however, for their submerged forests, some-
times seen on the foreshore between tide -marks,
sometimes laid open in the extensive dock or har-
bour works. The Heysham Harbour excavations,
for instance, were carried far below sea-level and
a thin peat-l)ed Mas met with in a boring at 52 feet
below Ordnance datum. Mellard Reade considered
this peat once to have been continuous with an

V] IRISH SEA AND BRISTOL CHANNEL al

ancient land-surface seen between tide-marks. A
boring is not altogether satisfactory evidence for
the occurrence of a land-surface at such a depth;
but if it is trustworthy it points to a subsidence of
about 60 feet, an amount identical with that observed
in the Thames Valley.

The estuaries of the Ribble, Mersey, and Dee tell
a similar story, for on their shores and under their
marshes are found some of the most extensive sub-
merged land-surfaces now traceable in Britain. Many
accounts of these have been published ; but the alter-
nations of marine with freshwater strata and with
land-surfaces are so like those already described that
a short account will suffice.

Carefully plotted engineer's sections will be found
in Mellard Reade's papers, and his account of the
succession is so interesting that it is worth quoting.
He postulates two periods of elevation, alternating
with three periods of depression ; but in this area,
as in the Thames Valley, it appears as though all the
phenomena can be accounted for by one long period
of intermittent depression. His generalised section
of the deposits in these estuai'ies is as follows : —

(Blown sand
Eecent silts with beds of peat ; Scrobicularia, occa-
sional freshwater shells, red-deer, horse, Bos
primigenius, Bos lomjifrons, and human skull

2nd period 1 „

|- oupenor peat- and forest-bed

4—2

52 SUBMERGED FORESTS [oh.

/ Formby and Leasowe marine beds ; human skele-

,. , . .,' ton, bones of horse and red-deer, Scrobicularia,

ot depression la,,,.,,,.,,,.,,, . ,

^ lellina baitica, I urntella co)iunitiiis, etc.

1st period ) ^ , . , „ , -,

, , ,. > Inferior peat- and forest-bed
of elevation ) *^

. , ( Washed drift-sand (apparently no contemporan-
1st period \ e ■^ ^

, . . J eous fossils)

of depression 1 „ , , ,
^ ( Boulder clay

It may be an accidental coincidence ; but it is note-
worthy that both the Mersey and Thames show two
main peat-beds separated by marine strata.

The forest exposed on the foreshore at Leasowe
(fi'ontispiece) is a particularly good example of these
old land-surfaces, and it is often visible. It evidently
once formed a wet, peaty flat on which grew swamp
plants, brushwood, and some large trees. Parts of it
show a perfect network of the rhizomes of Osmumla.
This "superior peat and forest-bed" was foiming when
the sea was only a few feet below its present level.
The ''inferior peat and forest-bed" probably indicates
a drier soil ; but it is difficult to get at and requires
fuller investigation.

The excavation for an extension of the Barry
Docks, in Glamorganshire, exposed in 189.3 an in-
teresting succession of deposits, and fortunately a
particularly competent observer, Dr Strahan, was
on the spot to note them and their exact levels.
He also obtained masses of material from eacli of
tlie beds, and from an examination of the contents

V] IRISH SEA AND BRISTOL CHANNEL 53

of these I was able to gather a clear idea of the
changes of sea-level which had aflected this part
of South Wales, The following sequence was met
with : —

1, Blown sand, ^

2, Sci'obicularia-cl-dj Recent subaerial

3, Sand and gravel with rolled Y and
shells {Scrohicularin, Tellina, Car- tidal deposits.
dium, Patella, LiUorina). I

Strong line of erosion.

4, Blue silt with many sedges, and at the bottom
a few foraminifera.

5, The Ujjper Peat Bed, about four feet below
Ordnance datum and fairly constant in level. It
ranges from one to two feet in thickness, and where
fully developed it presents the following details: —

5 a. Laminated peat with logs of Avillow, fir
and oak, passing down into

5 b. Light-coloured flexible marl composed of
ostracoda with much vegetable matter.

5 G. Shell-marl composed principally of Lim-
naea, Bythinia, etc., with ostracoda and much vege-
table matter. This seam must have been formed in
a nearly freshwater tidal marsh ; it yielded Najas
marina, a plant now confined to Norfolk.

5 d. Peat with logs of oak, etc. A Neolithic
worked flint was found by i\Ir Storrie in this seam,
three inches below the shell-marl. This implement

54 SUBMERGED FORESTS [ch.

is a fragment of a polished flint celt, which seems to
have been used subsequently as a strike-a-light. Two
bone needles are said to have been found in this peat-
bed during- the construction of the first Barry Dock.

6. Blue silty clay with many sedges. From five
to seven feet in thickness.

7. The Second Peat is an impersistent brown
band, a few inches in thickness, composed mainly of
Scirpus maritimus. It suggests merely that for the
time plant-remains were accumulating more rapidly
than mud.

8. Blue silty clay, like Nos. 6 and 4. In its upper
part, immediately under the peat bed Xo. 7, it con-
tains land and salt-marsh shells, Helix arhustonim,
Pupa, Melam2ms myosotis, Hydrohia ventrosa. Up-
right stems of a sedge, probably Scirpus maritimus,
occur throughout this bed as through all the other silts.

9. The Third Peed occurs at or close to the
bottom of the dock, at 20 feet below Ordnance datum.
It rarely exceeds eight inches in thickness, but is
persistent. In several places it is made up almost
entirely of large timber, both trunks and stools of
trees, while in one section roots and rootlets ex-
tended downward from the peat into a soil composed
of disintegrated Keuper Marl. Mr Storrie identified
oak and roots of a conifer. On washing a sample
collected at a few yards' distance, I found it to con-
sist of a tough mass of vegetable matter, principally

V] IRISH SEA AND BRISTOL CHANNEL 55

sallow and reed, both roots and stems. It also con-
tained seeds of Valeriana officinalis and Carex, and
elytra of beetles. There was no evidence of salt water.
At this point it will be observed that the floor
of Keuper Marl rises, and Bed 9 abuts against it.
Beds 10, 11 and 12 lay below the dock bottom, and
were exposed only in the excavation for the founda-
tions of walls, etc. Fortunately, Dr Strahan was able
to examine a good exposure of the important part
of them.

10. The section commenced at the dock bottom —
that is, at the peat last described (No. 9) ; in the
upper part it was timbered up, but at a depth of
about nine feet, blue silty clay of the usual character
could be seen and dug out through the timbers. This
was followed by two feet of greenish sandy silt full
of reeds, and containing leaves of willow, and land
and freshwater shells, such as Limnaea aurlcnlaria,
Planorhls albus, P. nantUem, Hydrohia ventrosa,
Valvata plscinalis, V. cristata. The plants were
Salix Ga2?rea and Phragmites.

11. Peat with much broken oak-wood, mixed
with seeds and freshwater shells. The plants ob-
tained were oak, hazel, cornel, hawthorn, bur-reed
and sallow.

12. Reddish clayey gravel with land shells and
penetrated by roots, passing down into red and
green grits, limestone and marls. This gravel is

56 SUBMERGED FORESTS [ch.

undoubtedly an old land-surface, lying at a depth of 35
feet below Ordnance datum. This old soil contains : —

Carychium minimum Pupa

Helix arbustorum Valvata piscinalis

,, rotundata Cardium edule (two fragments —
,, hispida probably brought by gulls)

Hyalinia Crataegus Oxyacautha (seed)

Succinea Cornus sanguinea (seed)

Limnaea truncatula Quercus Robur (wood)

The examination of these deposits made it per-
fectly clear that the lowest land-surface represents
a true forest-growth, such as could only live at an
elevation clear of the highest tides ; one tide of
brackish water in the year would have sufficed to
alter markedly the character of the fauna and flora
of the deposit. Dr Strahan, assuming that the range
of the tides was the same as at the present day, and
noting the present highest level to which the salt-
marshes reach, comes to the conclusion that 55 feet
at least is the amount of the subsidence. I should
be inclined to add a few feet more, in order to keep
the oak-roots well clear of the highest tide during
a westerly gale. An exceptional gale occurring»oidy
once during the lifetime of an oak might bank up
the sea water sufficiently to kill the tree, if it grew
at a lower elevation.

It may be argued that when the land stood at
the higher level the range of the tides was less,
and that consequently the amount of the ])rove(l

V] IRISH SEA AND BRISTOL CHANNEL 57

subsidence may not be so great as 55 feet. The old
land-surface on which the oaks grew lies, however,
35 feet below mean tide, so that any supposed lesser
tidal range in ancient times could not make any great
difference in the amount of subsidence here proved —
it cannot be less than 45 feet. When, however, we
notice the rapid increase in the range of the tides
at the present day as the channel narrows towards
Chepstow, and think wiiat would be the probable
efiect of raising the Avhole country 50 or 60 feet,
we are compelled to think that any narrowing and
shoaling of the channel would have the effect of in-
creasing, not decreasing, the tidal range at Barry
Docks. In short it looks as if when the lowest sub-
merged forest grew, the abnormal tides of Bristol
may have extended further west, to near Cardiff.

Whatever may have been the exact range of the
tides in these early days, it seems that the Bristol
Channel points to a subsidence in post-glacial times
of about 60 feet — or just the same amount as the
Thames, Humber, and Mersey. The amount may have
been more ; but the Barry Dock sections show that it
cannot have been less ; we will return to the question
of its maximum extent later on.

Before leaving this locality it may be well to en-
quire what further light it sheds on the movement
of submergence, and on its continuous or intermittent
character. The succession of the strata above the

58 SUBMERGED FORESTS [ch.

lowest land-surface, and the nature of their enclosed
fossils, suggest long-continued but intermittent sub-
sidence ; I can see, however, no indication of a reversal
of the process. The land-surface is carried beneath
the water, the estuary then silts up, becomes fresh
water, marsh-plants grow, and even trees may flourish
on this marsh before it subsides again. But there is
no sign that the strata were ever raised above the
level to which ordinary floods could build up an
alluvial flat. The land-surfaces seem always to have
been swampy, and bed succeeds bed in fairly regular
sequence, without the deep channelling we might ex-
pect to find when an alluvial flat was raised to a
noticeable extent above the level of high water.

The width of the Bristol Channel makes it clear
that this gulf must occupy a submerged valley of
great antiquity. It becomes therefore of interest to
enquire whether the wide valley is correspondingly
deep, or whether its rocky floor is found at the same
shallow depth as in the case of the other river-valleys
which we have been considering. The wide valley
may have been formed in either of two ways. It may
have been excavated as a deep valley with its bottom
many hundred feet below the present sea-level. Or
it may have conmienced as the shallow valley of a
big river with exceptionally powerful tides, and as
this river swung from side to side it greatly widened
its valley without making it any deeper.

V] IRISH SEA AND BRISTOL CHANNEL 59

Possibly a deep channel may exist towards the
Atlantic ; but we know that none extends as far up
as Bristol. Near Bristol the Severn Tunnel was
carried through Carboniferous and Triassic rock, and
showed that no buried channel is found much below
the present one, which here happens to be scoured
by the tides to an exceptional depth. The bottom
of the old channel cannot be more than 40 feet below
the bottom of the present channel known as The
Shoots.

It may be that the Severn was once prolonged
seaward as a swift river falling in a series of rapids
over hard ledges of Palaeozoic rocks ; but of this
there is no evidence. It also does not seem probable,
for all the geological indications go to suggest that
west of Bristol the Cliannel coincides in the main
with a wide area once occupied by comparatively soft
Secondary or even Tertiary rocks. However this may
be, we can only trace an ancient post-glacial channel
cutting to about the same depth as the channels of
the other rivers, and the lowest submerged land-
surface of Barry Docks corresponds quite well with
an alluvial flat formed when the river ran at that
level. Here again we seem to find the river cutting
to an ancient base-level which was about GO feet
below tiie present sea.

The reader may perhaps think that this point,
the limited range of the upward and downward

60 SUBMERGED FORESTS [ch.

movements in post-glacial times, is being insisted on
with wearisome iteration. But the insistence is
necessary when we remember how constantly both
geologists and naturalists, in order to account for
anomalies in the geographical distribution of animals
and plants, bring into play such movements. The argu-
ment is constantly used, that a certain species cannot
cross the sea : therefore if it is found in an island, that
island must once have been connected with the main-
land. Nature is more full of resource tlian we imagine,
and does not thus neglect her children. The cumu-
lative effect of rare accidents spread over many
thousand years is also far greater than may be
thought by those who only consider what has been
noted since means of dispersal have been studied
scientifically.

An examination of the south side of the Bristol
Channel need not long delay us, except for two pieces
of evidence whicli should not be passed over. In
Somerset there are wide expanses of marsh land
known as the Bridgwater and Glastonbury Levels.
These greatly resemble the Fenland, and like it are
underlain by a submerged rock-platform which has
sunk in post-glacial times. But in this case we are
able to fix a definite historical date by which all move-
ment had ceased — it may have ceased nuich earlier,
but we can prove that at any rate there has Iwjen no
change of the sea-level subsequent to a certain date.

V] IRISH SEA AND BRISTOL CHANNEL Gl

The Glastonbury Levels lie at about the height
of ordinary high tides, and the channels through
them would still be tidal were it not for the banks
which keep out the sea. Some years ago there were
discovered on the surface of these marshes a number
of low mounds, which on excavation proved to be the
remains of a village of lake-dwellings, approached by
a boat-channel, by the side of which were the remains
of a rough lauding stage. The dwelling-places rested
on the old salt-marsh vegetation, brushwood and soil
being used to raise their floors above the level of the
highest tides. It is evident that when this village
was inhabited the sea-level must have been the same
as now, or within a foot or two of its present height.
If the sea-level was then higher, the village could not
be inhabited ; if it were lower the channel would not
have been navigable and the landing stage would
have been useless. The archaeological i-emains found
in this village prove that it belongs to a period dating
about the first century B.C. or the first century a.d.

Another locality on the south side of the Bristol
Channel which we must not pass without notice is
Westward Ho, in Bideford Bay. There is nothing
exceptional about the submerged forest at this place,
but it has been carefully studied and collected from
by Mr Inkermann Rogers, and it may be taken as
a typical example of such deposits in the south of
England.

(J2 SUBMERGED FORESTS [ch.

The peaty deposits and old land-surface here seen
between tide-marks are rapidly being destroyed by
the sea and are now much thinner than they were
a few years since. The soil on which the trees, here
mainly oaks, are rooted consists of a blue clay full of
small pebbles and fragments of the Culm Measure
grit. Among these stones are numerous flint-flakes
made by man ; but metal implements and pottery, so
common in the later deposits at Glastonbury, have
not been found. This ancient land-surface lies several
feet below high water; it shows therefore that the
latest movement of depression dates from a i)eriod
between this Neolithic deposit and the Celtic lake-
dwelling of Glastonbury.

The possibility of fixing an ajiproximate date for
this submerged forest, tlirough its numerous flint-
flakes and the accomi)anying bones of domesticated
animals, makes its contents of great interest, for it
shows how recently the movement has ceased —
probably not more than li'AH) years ago. It will be
worth while therefore to give a fuller account of ti»e
contents of this soil and its overlying peat-bed.

As regards articles of human workmanship, I have
seen nothing but waste flakes of flint and perhaps
flint knives ; and though good implements may at
any time be discovered, neither chipped nor polished
tools seem yet to have been found. Human remains
arc re[)resented by a clavicle.

V] IRISH SEA AND BRISTOL CHANNEL 63

The accoinpaiiying mammals are the stag, Celtic
shortliorn, horse, dog (a very slender breed), sheep,
goat, and pig, all of which, except the stag, seem to
be domestic animals. Dr Chas. Andrews remarks that
the ox seems to be certainly the Celtic shorthorn
{Bos longifrons), while the small sheep is a character-
istic Romano-British form, which has been described
from many places, where it has been found with
Roman and earlier remains.

A number of seeds were obtained from the peat
which rests on this old land-surface, and it is notice-
able that several of them belong to brackish water or
sea-coast plants. No cultivated species have yet been
found, either here or elsewhere, in even the newest
of tlje submerged forests. The list of plants is still
a small one; but it may be worth giving, to show
what si)ecies can be identified. It must not be
forgotten that in such deposits plants which do not
possess either deciduous leaves or hard seeds leave
no recognisable traces, though they may have been
quite as abundant as the hazel, of which everyone
notices the nuts. Tlie seeds belong to: —

Ranunculus Flammula Rubus fruticosus

, , repens Callitriche

,, sceleratus Cornus sanguinea

Viola Sambucus nigra

Malachium aquaticum Aster Tripolium

Stellaria media Solanum Dulcamara

Lychnis Flos-cuculi Ajuga reptans

64 SUBiMKUUED FORESTS [CH.

Bueda maritima Quercus robiir

Atriplex patula Alisnia Plautago

Bamex KupjDia luaritima

Urtica dioica Eleocharis palustris

Alnus glutinosa Scirpus Tabernaemontani

Corylus Avellana Carex 3 sp.

In this list, as is usually the case Avith the newest
submerged forest, we find onlj^ plants that are still
living in the immediate neighbourhood. Also, only
such plants as are widely distributed are here found
as fossils, the characteristic west-country flora being
unrepresented. The reason of this limitation will be
discussed later.

For various reasons, which will be explained later,
it will be well before describing the submerged land-
surfaces of Cornwall and the Atlantic coast, to com-
plete the account of those surrounding our enclosed
seas. We will therefore take next those bordering
on the English Channel.

CHAPTER VI

THE ENGLISH CHANNEL

The English Channel, like our other enclosed seas,
is bordered on either side by a fringe of ancient
alluvia and submerged forests, wliich however are
fast disappearing through the attacks of the waves.
The destruction is so rapid, and in many parts has

VI] THE ENGLISH CHANNEL 65

been so complete, that we are apt to forget how
altered is the appearance of the English coast. Even
so recently as the time of Caesar's invasion flat
muddy shores or low gravelly plains occupied many
parts of the coast where we now see cliffs and rocky
ledges.

We will not labour this point, which must be
obvious to anyone who has noticed how little the low
terrace Avhich still fringes great part of the Sussex
coast can resist the waves, and how quickly it is
eaten away during storms. Any restoration of our
coast-line for the time of Caesar must take these
changes into account.

The material thus being removed by the attacks
of the sea is partly Pleistocene gravel, partly alluvium
of later date ; and the alluvial strata with their
accompanying buried land-surfaces resemble so
closely those already described that we need not
linger long over their description.

If we commence at the Strait of Dover we are
immediately confronted with clear evidence of the
change of sea-level. Submerged forests are well seen
between tide-marks in Pegwell Bay, and valleys with
their seaward ends submerged and forming harbours
are conspicuous in Kent. Owing to local conditions,
the valleys are mostly narrow and steep, and the
small harbours therefore soon filled up, or were lost
through the cutting back of the cliffs on either side.

H. 5

66 SUBMERGED FORESTS [ch.

Possibly in Caesar's day good natural harbours were
still in existence here.

Unfortunately on this part of the coast the study
of coastal changes has been involved in a good deal
of needless obscurity. Many writers, even geologists,
make no clear distinction between loss by sub-
mergence and loss by marine erosion. We are told,
for instance, that the Goodwin Sands were land about
900 years ago, and that this land disappeared during
an exceptional storm. We are sometimes even told
that here and elsewhere walls are still visible beneath
the sea. Popular writers, to add to the confusion,
have some hazy notion that these changes are con-
nected with the existence of submerged forests or
" Noah's Woods," and that these again are evidence
of a universal deluge. The whole of the arguments
are strangely tangled, and we must try and make
things a little clearer before passing on. An under-
standing of the changes which have taken place on
this part of the coast is needed for historical purposes,
and still more needed if we make a study of the origin
of the existing fauna and flora of Britain.

One of the crucial questions, both for the
naturalist and archaeologist, is the date at which
Britain was finally severed from the Continent. Did
this happen within the range of written history, or
tra<lition^ Or if earlier, did it take place after or
before climatic conditions had become such as we

VI] THE ENGLISH CHANNEL 67

now experience? For tlie proper understanding of
many different problems it is essential to settle this
point.

It is scarcely satisfactory to read history back-
wards, tliough geologists are often compelled thus
to work from tlie known to the unknown. We will
therefore not in this case ask our readers to follow
us through the detailed evidence and arguments
which have enabled geologists stage by stage to
reconstruct the physical geography of this part of
Britain as it was in days before written history. They
must take this preliminary work for granted, and
allow the description of the changes to be taken in
their correct historical order.

We need not go back far geologically. In late
Tertiary (probably Newer Pliocene) times there was
a ridge of chalk joining the range of the North Downs
to the corresponding hills of France ; but the divide
between the North Sea and the English Channel was
low at this point. Afterwards, during the Glacial
Epoch, when an ice-sheet accumulated and blocked
the northern outlet of the North Sea, the water was
ponded back in the southern part. There was no
easy outlet northward for the M'ater of the Rhine and,
other great rivers, so the level of the North Sea rose
slightly till it overflowed this low col and cut an out-
let where lies the present Strait of Dover.

The general sea-level during this period of

5—2

68 SUBMERGED FORESTS [ch.

gluciation seems to have been a few feet higher
than that of the present day, for glacially transported
erratics are found strewn over the flat coastal plain
of Sussex. One erratic block, probably derived from
the Channel Islands, was discovered under the loess
as far east as Sangatte clift', close to Calais. The icy
English Channel must therefore have met the icy
North Sea some time during the Glacial Epoch.

Some time after the cold had passed away there
came in the period with which this book deals — when
the lowest submerged forest flourished, on land now
50 or 60 feet below the sea. This elevation of the
land, as already shown, converted a great part of the
North Sea into a wide alluvial plain. At the same
time it raised above the sea-level and obliterated the
newly-formed strait, leaving it in all probability as
a shallow valley sloping both ways and filled up with
alluvium. The Strait of Dover was again a water-
shed, or perhaps its position was occupied by a small
stream, which may have flowed in either direction.

Thus the work done during the Glacial Epoch was
almost cancelled and had to be done again ; but now
there was merely a low narrow divide of chalk and a
strip of marsh between the two basins, and the chalk
ridge was steadily l^eing attacked by the waves of the
sea from the west.

When subsidence again set in the strip of alluvium
was soon submerged and the two seas again met ; but

VI] THE ENGLISH CHANNEL 69

in all probability for a long time the Strait was only
a narrow one, over which animals could easily swim.
Then tidal scour, deeper submergence, and the action
of the waves did the rest, so that ever since that time
the Strait of Dover has been getting steadily wider
and wider, and also deeper. Its bottom is to a large
extent composed of bare chalk with patches of gravel ;
and the movement of this gravel during storms, com-
bined with the action of boring molluscs must slowly
eat away the chalk far below ordinary wave-action.

The above explanation is needed, for it will not
do to take existing soundings, and say that all the
sea-bottom below a certain level, corresponding with
a particular submerged forest, was then sea and all
above was then land. This is an easy way of recon-
structing the physical geography ; but it may be a
very misleading one. A little consideration will show
that whilst in large areas sandbanks have accumulated
to a great thickness, in other areas, of which we know
the Strait of Dover is one and the Dogger Bank a
second, there has been much submarine erosion,
which is still going on. In neither case is it safe
entirely to reconstruct the ancient contours from the
present-day soundings.

Even such a gigantic feature as the continental
platform, which ceases suddenly at a depth of
100 fathoms, is in all probability in the main a
feature formed by the deposition of sediment during

70 SUBMERGED FORESTS [ch.

long ages. Its outer edge marks, not the limit of
some ancient continent, but the limiting depth at
which gentle wave-action has been felt, and beyond
which the sediment cannot be carried.

After this necessary digression we must return to
our study of the actual evidence for such changes of
sea-level in the English Channel. It has been pointed
out already that for this purpose the present depth
below sea-level of the rocky floor of the Strait cannot
m itself be accepted as suflicient evidence. Nor can
the depth at which rock was met with under the
Goodwin Sands ; though here a cylinder was sunk
75 feet before it reached the chalk. Unfortunately
no record of the strata passed through seems to have
been preserved, though it is perhaps implied that
nothing but sea-sand was penetrated.

Romney INIarsh is a wide alluvial flat occupying
a silted-up bay, the floor of which in places lies at
least 70 feet below sea-level. There are here un-
fortunately no extensive excavations for docks, and
all we can say is that the few borings which have
penetrated the alluvial strata prove the existence of
a slightly luidulating rock-surface below. In short
Ronmey Marsh appears to be a submerged flat-
bottomed open valley, like that which we have
already seen underlies the marsh deposits of the
Fenland.

In the case of Romney Marsh, however, it is

VI] THE ENGLISH CHANNEL 71

doubtful whether submerged land-surfaces would be
found at any great distance from the rising ground.
There is a striking peculiarity about this marsh; it
only lies partly in a bay, the greater part of the area
consisting of alluvial flats which have accumulated
during recent centuries behind the projecting shingle
beaches of Dunge Ness. In short, the marsh steadily
gains on the sea, is advancing into fairly deep water,
and the parts near the Ness may be underlain by
marine strata right down to the Wealden rocks below.
The rock floor was met with at 58 feet below the
marsh at Holmston Range, not far from the Ness ;
but we have no information as to the character of
the strata passed through before this floor was
reached. In all probability this floor at 58 feet
would be proved to be part of a true land-surface,
could we examine it.

Near Hastings the submerged forests have long
been knoMu, and are often exposed on the foresliore
between tide-marks. They contain antlers of deer,
leaves, hazel nuts, acorns, and oak wood.

Then we come to Pcvensey Level, which is another
of the submerged and silted up wide flat-bottomed
valleys, such as we have so often met with. But as
we have no details as to strata underlying this marsh
we must pass on.

Along the Sussex coast west of Beachy Head a
series of south-flowing rivers reaches the sea, each

n SUBMERGED FORESTS [ch.

cutting through the high chalk-hills of the South
Downs. We need not discuss the origin of these
peculiar courses, which date back to the period when
the central axis of the Weald was uplifted ; that
discussion would take too much time, and is here
unnecessary. We are now only concerned with the
later stages of the evolution of these river-valleys,
each of which yields striking confirmation of the view
that a sinking of the land has taken place in com-
paratively modern times.

At the present day the tidal part of each of these
rivers extends right through the Downs into the
lower Wealden area, and it is obvious that their
valleys tend to silt up, not to deepen, and scarcely
anywhere to become wider. When we examine
further we find that the true valley-bottom lies
far below the present alluvial flat ; though the
scarcity of borings and the uncertainty of many of
the records make it difficult to say exactly how deep
it lies.

If we follow these rivers upwards we find that in
each case the alluvial flat widens out gi-eatly after
we have passed the chalk-hills and reached the clay
lands beyond. These wide flats, according to old
ideas, were formed by the swinging from side to side
of the stream, which thus gradually widened its valley
in the softer strata. If this were the case in tiiese
instances, we should find a solid floor beneatii each

VI] THE ENGLISH CHANNEL 73

marsh at a depth not exceednig that of the present
river-channels. The rivers, however, are not now
cutting into rocky banks or flowing over beds of
Secondary strata ; they are flowing sluggishly in the
middle of alluvial flats, which tend to silt up with
every flood or exceptionally high tide.

Thus all the evidence seems to show that marshes
like those near Lewes and Amberley Wild Brook
have originated through the submergence of flat-
bottomed valleys cut in soft strata. The ponding
back of the muddy tidal water would soon lead to
the silting-up of any shallow lakes left after this
submergence.

When the land stood 70 or 80 feet higher than it
does now, the country must have looked very ditFerent.
The rivers then traversed the chalk downs through
V-shaped comparatively narrow valleys; but these
valleys opened out in their upper reaches, where
they crossed the Gault and Weald Clay. If we coidd
lay bare the true floor of the valley, we should see
however that there is always a steady and fairly
regular fall seaward, just as there is in the part of
its course which lies above the influence of the
submergence, which is felt for some 10 or 12 miles
from the sea. Except on this theory of recent sub-
mergence it seems impossible to account for these
curious marshes, with tributary valleys obviously
plunging sharply beneath them on either side ; they

74 SUBMERGED FORESTS [ch.

are quite unlike the undulating flats Avhich occur
higher up.

The flat of Selsey Bill yields evidence of sub-
merged land-surfaces opposite each of the shallow
valleys ; but here we meet with the same difficulty
which confi-onted us in the Thames Valley and on
the east coast. Pleistocene land-surfaces and alluvial
deposits of early date are seen on the foreshore side
by side with the more modern Neolithic alluvium and
submerged forests. Unless great care is taken it
may be thought that the well-preserved bones of
rhinoceros and elepl'.ant, and the shells of Corhicula
Jium'uialis, come from the same alluvium that yields
Neolithic flint-flakes, or that plants such as the
South European Cofoneaster Pyracantlia flourished
in Britain up to this recent date. Except for the
sake of warning against these sources of error the
submerged forests of Selsey Bill need not detain us.

Still travelling westward we next arrive at the
series of tidal harbours opening into Spithead,
Southampton Water and the Solent. All of these
are obviously continuations of the valleys which
lengthen them inland ; and this is amply proved by
dock excavations and borings.

Even Southampton Water and the Solent them-
selves are nothing but submerged valleys. A well at
the Horse Sand Fort — one of the iron forts which
rises out of the sea at Spithead — showed a band of

VI] THE ENGLISH CHANNEL 76

compressed vegetable matter, probably an old land-
surface, more than 50 feet below high-water level,
the floor of Eocene strata not being met with till
98 feet below high water was reached. In this case,
however, the strata below 50 feet seem, from the
published description, to be of marine origin.

The well at Norman Fort is stated to have pene-
trated to a depth of 12/ feet below the sea before
Eocene strata were reached ; but in this case the
lower strata were of marine origin, and the only
land animal recorded was a jaw of red deer, found
apparently between 80 and 90 feet down. These
deep channels may be relics of the very ancient
(Tertiary) Solent River, and were probably arms of
the sea till they were sufiiciently silted up for the
lowest submerged forest to grow.

We have not yet sufficient data, nor is it necessary
to our purpose, to give a detailed reconstruction of
this interesting area during the successive stages of
elevation and depression. During the time when
the lowest of the submerged forests flourished the
Isle of Wight was connected with the mainland
where the Solent now narrows about Yarmouth, and
probably for some distance westward. This connexion
was kept up till comparatively recent times, only
breaking down finally a short time before Caesar's
invasion.

In early Neolithic times the ancient Solent Valley

76 SUBMERGED FORESTS [ch.

had already been decapitated by the inroads of the
sea west of the Needles, and the remains of this big
valley were occupied by a small river flowing east-
ward through the middle of the present Solent. In
its course it received numerous tributaries on either
side. It probably opened out into an estuary where
it joined Southampton Water, and so continued to and
beyond Spithead, receiving other tributaries from
the valleys now occupied by Portsmouth Harbour,
Langston Harbour and Chichester Harbour.

In time we may be able to make a more complete
reconstruction of the physical geography of this area
for definite dates ; but the point now to be insisted
on is that the Isle of Wight was part of the mainland
up to quite recent times, so that its fauna and flora
could readily pass backwards and forwards without
crossing the sea.

Perhaps to the geographer or geologist one of the
most striking confirmations of a recent submergence
afi'ecting this part of England will be found in the
strange series of enclosed harbours extending from
Chichester westward to P^areham. These harbours
are not each distinct and separate ; all of them have
cross connexions in the form of shallower channels
some four or five miles inland from Spithead. I have
often been asked what is the meaning and origin of
these peculiar harbours, which are not forming or
widening now, but rather tend to silt up.

VI] THE ENGLISH CHANNEL 11

The origin of these harbours is quite easy to
understand, if we admit the recent sinking of the
land, and for this we will presently give abundant
evidence. On any other hypothesis these inosculating
water-ways must seem hopelessly confused and in-
explicable. Sea and waves do not erode enclosed
basins such as these.

Granting the submergence, we see that each of
these harbours must once have been a shallow valley ;
but this does not account for their basin -like shape
and their cross connexions. For the reason of these
peculiar features we must look at the map by the
Geological Survey showing the superficial deposits.
It will then be seen that all this part of Hampshire
shows a widespread sheet of gravel and gravelly loam
which slopes gently seaward and passes below the
sea at Spithead. Northward the gravel rises, and
the soft Eocene and Cretaceous strata appear beneath
the gravel between tide-marks at various places to-
ward the northern ends of these harbours.

The waves of the sea can remove loose gravel as
readily as clay, and we see that on this coast wave-
action is practically confined to the low clifi" facing
the sea and does not affect the interior of the
harbour. But it is well known to geologists that a
sheet of coarse angular gravel such as this, notwith-
standing its looseness, is much less readily attacked
by a small stream than is a surface of hard clay or

r« SUBxMERGED FORESTS [ch.

even chalk. Thus plahis of Tertiary deposits capped
by gi-avel, under the action of rain or rivers develop
into gravel-capped plateaus and hills, which fall
abruptly into open flat-bottomed valleys. The denu-
dation takes place at the edge, where the gravel rests
on the Tertiary strata and numerous springs are
given out ; tliere is scarcely any denudation in the
gravel flat, and unless the height of the land is
considerable there is no great amount of denudation
in the flat bottom of the valley.

Thus there is a tendency for the valley to widen
out on every side, wherever the gravel rests on
impervious or soft strata. But where the gi-avel
l)lunges below the water-level, as it did at the
entrance to each of these harbours, the valley
narrowed, for there were no landslips, the drainage
was subterranean, and the stream could not readily
lemove the large flints.

J'he widening of the valleys, where they were cut
in soft strata, led to the development of small lateral
valleys to the right and left, leaving only narrow
divides between their head waters and those of the
next valley. When the land sank these divides were
flooded, and so were developed the shallow cross
connexions, much as we now see them.

In order that it may not be imagined that this
reconstruction is merely hypothetical, it will be as
well to give sonie evidence that such an elevation

VI] THE ENGLISH CHANNEL 79

and submergence did take place in this district as in
others. We cannot in this little book deal with the
whole of the evidence, so we will take the Southampton
Dock excavations as sufficient to prove our point, con-
densing the account from the Geology of Southamptou^
published by the Geological Survey.

The general section at Southampton Docks is as
follows, though the thickness varies considerably at
different points, and the greatest depth of the old
valley has not yet been proved : —

Feet
Estuarine silt . . . ... ... ... ... 20

Peat, old vej^etable soil, or tufaceous marl ;

ox, pig, horse, piue, beech, birch, oak,

and hazel ... ... ... ... variable up to 17

Cxravel, with reindeer ... ... ... 10 or more

The bottom gravel is apparently of Pleistocene date,
though it may include also a basement bed belonging
to the newer deposits. T. W. Shore recorded from
the peat above the gravel a fine stone hammer-head
of Neolithic date and worked articles of bone, but no
instruments of metal were found. The associated
marl was full of freshwater shells.

Poole Harbour tells a similar story, and evidence
of this submergence is seen in the various submerged
forests found along the Dorset and Devon coasts,
opposite the mouths of the valleys. These rocky
coasts are, however, so different from those we have
just been describing, that they will more conveniently
be treated of in a separate chapter.

80 SUBMERGED FORESTS [ch.

CHAPTER VII

CORNWALL AND THE ATLANTIC COAST

On travelling westward into Cornwall we enter a
region which is extremely critical in any enquiry as
to the amount of change that the sea-level has under-
gone. As long as we were dealing with ancient river-
channels opening into enclosed seas, like the North
Sea or Irish Sea, it might be said that the depth
to which the channel was cut was not necessarily
governed by the sea-level. It might be governed by
the level of an alluvial plain, which then extended
for hundreds of miles further, and had its upper edge
high above the sea-level.

This cannot be said in Cornwall, for there the
sea-bed shelves rapidly into deep water, and the coast
would not be far away, even were the land raised
200 feet or 300 feet. The rivers then as now must
have flowed almost directly into the Atlantic Ocean,
and their channels must then as now have cut nearly
to the sea-level of the period.

The Cornish rivers yield most valuable information.
It so happens that many of them bring down large
quantities of tin ore fi'om the granitic regions, and
this ore being very heavy tends to find its way to the
bottom of the alluvial deposits, out of which it is

VII] CORNWALL AND ATLANTIC COAST 81

obtained in the same way as alluvial gold in other
countrie?. On following tiiis detrital tin ore down-
wards towards the estuaries the " tinners " or alluvial
miners found in many case^ that a rich layer descended
lower and lower till it passed well below the sea-level
in some of the ancient silted-up valleys. Some of
these tin deposits were so rich that it paid even to
divert the rivers, dam out the sea, and remove the
alluvium to considerable depths in search of the ore.

These excavations for tin produced most interest-
ing and continuous sections of the alluvial deposits,
and if only they had been examined more thoroughly
and scientifically they would have thrown much light
on the questions we are here considering. Unfor-
tunately all the deeper excavations were made in
days when all ideas as to the origin of "diluvial"
deposits were so tinged with tlieories as to the effects
of a universal deluge, that many of the most interest-
ing points escaped notice. Tiie last of tliese " stream
works " was closed many years ago.

Notwithstanding the early date of these ex-
cavations, some most interesting observations were
recorded ; and though they make us long for fuller
details and regret the loss of many of the objects
referred to, we must be grateful that so much was
noted, and by such careful observers. This entire
removal of the old alluvial deposits — for the tin
usually occurs concentrated in the bottom layers —

R. 6

82 SUBMERGED FORESTS [ch.

showed clearly that in Cornwall, as elsewhere, old
land-surfaces can be found far below the sea-level.
The shape of the valley-bottom, and the rapid lessen-
ing of its fall as the coast is approached, in several
cases point clearly to the proximity of the sea, and
show that its ancient level must have been about
70 feet below present tides.

Here it may be pointed out that as the sea-level
is approached the steady seaward fall of a rocky
V-shaped valley quickly lessens, changes to a gentle
slope, and then to a flat, more or less wide according
to the length of time during which the river has been
kept at the same level, and could only swing fi'om
side to side, without deepening its bed. In Cornwall
there is a definite limit below which the erosion of
the valleys has not gone, and at this level the valley
widens and flattens as it does elsewhere.

The eastern boi-der of Cornwall is formed by the
extensive harbour wlii(;h receives the Tamar, Tavy,
and Plym, and this hnrbour is obviously nothing but
a submerged seaward continuation of the combined
valleys eroded by these rivers. The rivers, it nuist
be remembered, though short, receive great part of
the drainage of Dartmoor, where the rainfall is ex-
cessive ; thev are therefore verv liable to floods. These
streams also bring down much coarse gravel and sharp
granitic sand, so that their erosive poAver nnist be
exceptionally great during floods. It seems therefore

VII] CORNWALL AND ATLANTIC COAST 83

that the scour would always have been sufficient to
keep open a channel well below low-water level.

No stream tin has been worked in the Plymouth
estuary, so that we cannot point to any continuous
sections in the ancient alluvial deposits, such as are
found further west. These tin deposits, however,
date in the main from a period somewhat earlier
than that with which we are now dealing. They were
probably swept down from Dartmoor when floods
were far more severe, during the annual spring
melting of the snow during the Glacial epoch. Un-
fortunately, also, the lately finished harbour works
at Devonport proved the existence of only modern
alluvium, without any submerged forests.

Before dealing with the rivers which flow into
Plymouth Sound it is necessary, however, to say a
few words about the harbour itself and its origin.
Plymouth Sound and the various submerged valleys
which open into it illustrate well both the continuity
of geological history, and tlie great difficulties which
await us when we deal with valley erosion which in
part dates far back into Tertiary times. The Sound
is not merely a submerged continuation of the
Pleistocene valleys, and between this wide gulf and
the narrow valleys there is a curious want of con-
tinuity. We do not know the true depth to the rocky
floor ; but at two places just outside the mouths
of the estuaries deep hollows are scoured through

6—2

84 SUBMERGED FORESTS [ch.

the sands. One of these, just outside the Hamoaze,
or estuary of the Tamar, shows a rocky bottom at
150 feet, probably the true rock-floor of that part of
the Sound. The other hollow, 132 feet, is just outside
the Cattewater ; but does not reach rock.

It is obvious that these depths, both of which are
measured from low water, show a depression of the
rocky floor of the Sound far greater than we meet
with in ordinary Pleistocene valleys ; but at present
we have no means of proving the true date of this
depression. It represents not improbably a Tertiary
basin, like that of Bovey Tracey, which also descends
several hundred feet below sea-level. In favour of
this view we can point to the occurrence of a small
outlier of Trias in Cawsand Bay, which certainly
suggests that the Sound represents an area of
depression or synclinal basin, rather than a mere
submerged valley. It has also been stated that relics
of Tertiary material are still to be found in the lime-
stone quarries of Plymouth ; but for this the evidence
is not altogether satisfactory.

It may be asked. What practical difference does
it make, whether or no the Plymouth Sound were
originally a Tertiary basin, for no Tertiary gulf could
now remain open ? If we were dealing with an area
of soft rocks, like the Thames Valley, or with an
enclosed sea, this objection would hold. Around
Plymouth, however, the Palaeozoic rocks are

VII] CORNWALL AND ATLANTIC COAST 85

extremely hard, and can resist for ages the attacks of
the sea ; but loose Tertiary material, or even Triassic
strata, would readily be swept away by the heavy
Atlantic swell and by the scour of the tides, until
they were protected by the building of Plymouth
Breakwater.

There is a general impression that marine action
cannot go on much below low water ; but this is
altogether a mistake. Tidal scour may go on at any
depth, provided the current is confined to a narrow
channel, so as to obtain the requisite velocity. If in
addition there is a to-and-fro motion, such as that
caused by tiie Atlantic swell at depths of at least
50 fathoms, the actual current required to remove
even coarse sand need only be very gentle. The
oscillation in one direction may not reach the critical
velocity ; in the other this velocity may just be
exceeded; the movement, therefore, of the sand
grains may always be in one direction, especially
if the courses taken by the ebb and flood tides
do not coincide, or their velocities difl^er.

How does this apply to the origin of Plymouth
Sound ? The mere fact that opposite the mouth of
the Tamar a pit has been scoured to a depth of
150 feet, and opposite the Hamoaze another to 132 feet
below low water, and that these pits are kept open,
notwithstanding the enormous amount of sediment
brought down by these rivers, proves that tidal scour

86 SUBMERGED FORESTS [ch.

is now going on, or was recently going on, at depths
of 25 fathoms at least in confined parts of Plymouth
Sound. Similar troughs occur at even greater depths
near the Channel Islands, M'here the tidal scour is
very great, and in the Bay of Biscay coarse sand is
moved at depths of at least 100 metres.

It is necessary to make this digression as to the
effects of tidal scour, for we are sometimes told that
the various basins, troughs, and channels shown on
the charts represent submerged land-valleys, and
thus prove enormous changes of sea-level in modern
times. How a submerged valley in a narrow sea with
sandy bottom, like the English Channel, could remain
long Avithout silting up is not clear ; the sandbanks on
either side should tend to wash into and fill uj) the
hollows. The troughs, however, all coincide with
lines of tidal scour ; they do not continue the lines of
existing valleys, unless these valleys are so large as
to produce a great scour, and unless this scour is
aided by the oscillation of the waves. A glance at
the Admiralty chart will show that no submerged
channel crosses the direction of the tidal scour or of
the Atlantic swell; the chaimels are scoured where
tide and swell act together.

We conclude therefore that Plymouth Sound pro-
bably represents a basin once filled with soft Tertiary
and Secondary deposits, and that these soft deposits
were cleared out by the sea, leaving the rocky floor

VII] CORNWALL AND ATLANTIC COAST 87

of the basin bare at a considerable depth below sea-
level. In part the basin has now silted up again ; but
we may fairly consider that at the time of greatest
elevation, when the submerged valleys were being-
eroded, the depth of water in the Sound was much
the same as it is now. Then as now the rivers seem
to have discharged into a wide open gulf occupied by
the sea.

However this may be, we see now a series of
deeply trenched valleys, partly submerged and all
opening into a wide and deep bay. These valleys do
not now show rocky bottoms gradually sloping into
the open harbour. The rock floor ceases several
miles up and gives place first to an alluvial flat and
then to an arm of the harbour. Like all the other
valleys with which we have been dealing they cut to
a definite base-level, approximately that of the sea,
and the parts below that level are rapidly silting up.

Fortunately a large series of bridge-foundations
has shown well the character of these valleys, where
the rocky floor passes beneath the sea-level, and the
late R. H. Worth gave an excellent series of sections
across them. He took their contours to be evidence
of glaciations. In this I cannot agree with him ; but
think rather that the extraordinary flatness of the
valley-bottoms, and especially the uniform depth to
which they were excavated, point to the attainment
of a definite base-level.

88 SUBMERGED FORESTS [ch.

Commencing- with the most easterly of the rivers

which enter the Sound, we find that the Laira Rail-

wa}' Viaduct, across the Cattewater, proved a breadth

of 212 feet at the centre of the channel, with the

rock-floor practically level at 87 feet below low water ;

no V-shaped valley or gorge was met with. At Saltash

the foundations of the bridge show the depth to the

rock-bottom to be 75 feet; but the viaduct across

the Hamoaze is about three miles higher up the river

than the Laira Viaduct. The Taw Viaduct, nearlv

two miles further from the sea, shows a width of 240

feet of practically level rocky floor at 67 feet below

sea-level. Thus all this evidence is consistent with

the existence of a series of wide open flat-bottomed

valleys, now partly submerged, with a fall of about

five feet in the mile. This is about tiie fall necessary

for even a rapid river flowing through a flat so full of

boulders and coarse gravel as this must have been.

It must not be forgotten also that tliis five feet in the

mile is the general fall of the valley-bottom, not of

the water, and that a river winding from side to side

would have about half or one-third of this fall. The

slope was probably just sufficient to keep the channel

clear and let the water escape.

We may take it, therefore, that the ancient valleys
opening into Plymouth Harbour cut to about 100 feet
below mean tide, as do the Thames and Humber, and
that this was the measure of the greatest elevation of

VII] CORNWALL AND ATLANTIC COAST 89

the land in Pleistocene times, for these valleys opened
suddenly into a sea of considerably greater depth.
A word of explanation is still required as to the
meaning of the extremely flat rock-bottom, for one
might have expected more of a U-shaped or V-shaped
valley, unless the period of stationary sea-level were
very long.

Owing to the great rush of water from Dartmoor
during floods, and the enormous amount of coarse
gravel swept down, the erosive power of these streams
is very great. This was greatly exaggerated during
the Glacial Epoch, to which the formation of the tin-
ground and of the flat bottom belong. The melting
of the snow in spring must have caused far more
severe floods than we now see, and these floods must
have brought down large quantities of river-ice heavily
charged with boulders of hard and angular meta-
morphic rocks, such as would erode and trench in a
way that does not now happen. Thus as the river
changed its course or swung from side to side accord-
ing to the varying amount of water, the ice-laden
water must have had an erosive power more like that
of a Canadian river in spring than like anything we
now see in Britain. The wide and deep flat-bottomed
trench need not have taken any enormous length of
time to form, for river-ice and anchor-ice were con-
stantly at work removing the loose material and laying
bare the rock-face so that it could be again attacked.

90 SUBMERGED FORESTS [ch.

The period of exceptionally rapid erosion and of
low sea-level above postulated must be our starting
point in Devonshire and Cornwall as elsewhere, for it
fixed the shape and depth of the submerged valleys
over wide areas. This erosion came someAvhat earlier
than the growth of the submerged forests ; but it is
impossible to treat of any particular period of history
without some mention of what has gone before and
led up to it. I may say also that I doubt whether
tliere is any such great gap as is commonly supposed
between the Glacial period and later times.

Unfortunately the succession of the newer deposits
in the submerged valleys near Plymouth appears
never to have been worked out, attention having
been concentrated on tiie contour of the rocky floor.
The recently completed Devonport dock excavations,
which I examined, showed only very modern alluvium
and silted-up channels with logs of wood cut by metal
tools. Submerged forests do not appear to have been
met witii.

Though Plymouth Harbour has not yielded much
information concerning the particular period with
which we are dealing, it is important as fixing tlie
maxinunn amount of elevation to which the land was
subjected in Pleistocene or more recent times. We
will now turn to the Cornish stream-tin works, which
give niore detail as to the later changes; wc regret
however tliat these most interesting excavations were

VII] CORNWALL AND ATLANTIC COAST 91

closed so long ago, for various points were noted
about which we should like furtiier information, and
this is not now obtainable. The old diluvian hypothesis
has much to answer for in the long neglect of those
modern strata which help to tie on geology to archae-
ology and history.

By far the best account that has come down to
us of a Cornish tin stream-work carried below the
sea-level, is that Avritten by J. W. Colenso in 1829.
Colenso had uinisual opportunities for watching the
works — apparently either as manager or owner — and
he showed a most exceptional ability to note scientific
points, such as were generally overlooked 90 years
ago. It should be remembered that even in days
before Lyell wrote we had in the Cornish tinners
a class of men whose everyday occupations led them
thoroughly to understand the action of running water.
Their daily bread depended on their power to calcu-
late where the ancient flood must have left the heavy
tin-ore, where the barren ground woidd be found, or
where old silted-up channels might be sought for. In
their arrangements for diverting the sti'eams in order
to work the alluvial deposits, and for washing and
concentrating the tin-ore, they were constantly brought
face to face with tlie action of running water. When
the buried tin-ground yielded anything abnormal the
tinner recognised the eftects of exceptional floods, of
eddies behind boulders, or of obstructing ledges.

92 SUBMERGED FORESTS [ch.

AYliere he thought he saw tlie action of the dehige
we may be pretty certain tliat he was dealing with
something truly exceptional and outside his experi-
ence of the effects of a mountain torrent. He was
not using the word as a cloak for ignorance or excuse
for indifference, as was so often the case with the
geologist of that day. Unfortunately most of the
tinners could not write.

Colenso's account is entitled A Description of
Happij Union Tin Sfream-worJi atPentuan. Pentuan
lies at the mouth of the St Austell River, a rapid
stream, much liable to sudden floods, which drains part
of the granite and metalliferous region of St Austell
Moor. The conditions are ideal for bringing down
large quantities of the decayed granite which contains
the tin-ore. This material was alternately weathered
and broken up, and so sluiced with flood-water as
to Avash away the lighter quartz and felspar, thus
concentrating the tin-ore, with a small amount of
gold-dust and small gold nuggets, in the bottom
layer.

The alluvium of the St Austell River was therefore
so profitable to work that every channel was followed
upwards into the Moor, and the main valley was
followed downward towards the sea. But as the
coast was approached the rocky floor sank below the
sea-level, so that this part was left till last, for it
needed the divei^sion of tlie river and much pumping

VII] CORNWALL AND ATLANTIC COAST 93

to get rid of the water. This, scientifically, is a
fortunate circumstance, for of the earlier workings in
the higher part of the valley no good accounts have
come down to us.

The river is only a small one and its catchment
area is very limited; it has therefore a rapid fall,
amounting to 30 feet in the mile between St Austell
and the sea. With this fall the valley is still silting
up and its alluvium rising, principally through the
abnormal amount of sediment and granitic sand sent
down by the china-clay works. If we take the fall of
the buried channel, this amounts to about 45 feet to
the mile, for the rock-floor at Pentuan lies about 60
feet below the sea-level. This rock-floor is composed
of hard slates.

The successive deposits met with above the slate
were as follows, commencing with the lowest : —

(a) The tin ground, or stratum in which the
whole of the stream-tin is found. It lies on the solid
rock and is generally from three to six feet thick,
sometimes even ten feet. It extends across the valley,
except where turned by a projecting hill or rock,
when it is found to take the supposed ancient course
of the river, which is generally under the steep bank
opposite. This last observation (often made by
tinners) is important, for it suggests that the heavy
tin-ore was brought down by exceptional floods, such
as would swing violently to the outer side of the

94 SUBMERGED FORESTS [ch.

curve, and there cut a steep bluff, under which would
be left the heaviest gravel. This observation and the
noteworthy absence of any contemporaneous animal
remains in the tin-ground, suggest that the bottom
layer may date back to Pleistocene times, when the
climate was colder and floods more violent.

It is not clear how far seaward the valley may
then have extended; probably not more than half
a mile at most. The tin ground was worked near
Pentuan for 1400 yards along the valley, and aver-
aged about 52 yards in breadth. So here again we
meet with a fairly wide flat-bottomed valley, not a
narrow V-shaped gorge; we may therefore take it
that the base-level had been reached and that this
base-level Mas identical with that met with in the
rivers which open into Plymouth Sound.

(h) On the tin ground were rooted numerous oaks,
Avhich had grown and fallen on the spot. Their timber
was so sound that Colenso applied one of the trees to
make the axle of a water-wheel, and his conunent on
this is excellent. "It appears to me likely that at
this period, the rising of the sea had so far checked
the current of the river as to prevent its discharging
the mud and sand brought down with it; thus the
roots were buried [submerged ?] to a considerable
depth, and the trees killed, before the timber under-
went its natural process of decay." At one spot he
records finding oysters still remaining fastened to

VII] CORNWALL AND ATLANTIC COAST 95

<

some of the larger stones at the top of the tin ground
and to the stumps of the oaks.

Then comes a stratum of dark silt, about 12 inches
thick, with decomposed vegetable matter, and on this
a layer of leaves of trees, hazel nuts, sticks and moss
for 6 or 12 inches more. This layer of vegetable
matter is about 30 feet below the level of the sea at
low-water and about 48 feet at spring tides. It ex-
tends with some interruption across the valley.

The point is not made quite clear in Colenso's
account, but apparently there is no marine deposit
between the "tin ground" and the peat, the oyster-
bed above mentioned representing the base of bed c,
which at that point has cut through the peat, so as
to lay bare part of the gravel and some of the oak-
stumps rooted in it. So far, wherever we have a
carefully noted section of the lowest deposits in these
valleys, the tin ground or the gravels are directly
succeeded by a growth of oak trees. It looks as
though the climate amelioi-ated, the more violent
floods ceased, and an oak forest grew across the allu-
vial flats, without there being any, or much, change
of sea-level.

(c) Above the vegetable matter and leaves (b)
was found a "stratum of sludge or silt" 10 feet in
thickness. It showed little variation except from a
brownish to a lead colour. "The whole is sprinkled
with recent shells, together with wood, hazel luits,

96 SUBMERGED FORESTS [cH.

and sometimes the bones and horns of deer, oxen, etc.
The shells, particularly the flat ones, are frequently
found in rows or layers; they are often double or
closed, with their opening part upwards." From
Colenso's account it seems probable that this bed was
a marine silt with Scrohicularia and cockles in the
position of life. He goes on to say that "There has
been recently found imbedded in the silt, about two
feet from the top, a piece of oak, that had been
brought into form by the hand of man ; it is about
six feet long, one inch and a half broad, and less than
half an inch thick ; this is the greatest depth at which
I have ever seen any converted substance. It appears
to have floated in the sea, as at one end, which is
much decayed, a small barnacle has fixed its habita-
tion."

{d) A stratum of sea-sand, about four inches in
tiiickness ; this is easily distinguished from the river-
sand, being much finer, and having always more oi-
less shells mixed with it.

(c) Silt two feet, with concretions containing
wood and bones.

(/) Another stratum of sea-sand, 20 feet in
thickness. In all parts of this sand there are timber
trees, chiefly oaks, lying in all directions; also re-
mains of animals such as red deer, "heads of oxen of
a difterent description from any now known in Britain,
the horns of which all turn downwards." Human

VII] CORNWALL AND ATLANTIC COAST 97

skulls were also found near the bottom of the sand,
and one of these with other fossils was presented by
Colenso to the Royal Geological Society of Cornwall.
In the upper part of this sand nearer the mouth of
the harbour, the bones of a large whale were found.
The sea at this time seems to have extended about a
mile up the valley.

{g) A bed of rough river-sand and gravel, here
and there mixed ivith sea-sand and silt. About 20
feet in thickness. In this sand was found "the re-
mains of a row of wooden piles, sharpened for the
l)urpose of driving, which appear to have been used
for forming a wooden bridge for foot passengers : they
crossed the valley, and were about six feet long ; their
tops being about 24 feet from the present surface —
just on a level with the present low water at spring-
tides. Had the sea-level been then as now, such a
bridge would have been nearly useless."

At Wlieal Virgin, which was the upward extension
of the Happy Union works, about a mile higher up
the valley than the bridge just mentioned, the tin
ground was only 32 feet from the surface. Here
Colenso mentions seeing "on the surface of the tin-
ground two small pieces of oak, with artificial holes
in them : and there were near them several oak stakes,
sharpened and driven into the ground, and supported
by large stones. Near the same spot has been found
a substance resembling the ashes of charcoal." This

R. 7

98 SUBMERGED FORESTS [oh.

account suggests a fish or otter trap of some sort and
the charcoal below the sea-level suggests that it must
date back to at least as early a period as the sub-
merged bridge. It is a great pity that antiquaries
were not at that period more alive to the great interest
of these finds.

Carnon stream-works, on a navigable branch of
the Fal, showed a very similar section, for below
about 54 feet of alternating sand and silt was found,
according to Henwood, a bed one and a half feet thick
of wood, moss, leaves, nuts, etc., a few oyster shells,
remains of deer and other mammals, and some human
skulls. Below this came the tin ground varying in
thickness from a few inches to 12 feet. Here also
no organic remains were found in the tin ground
itself.

The above records may be accepted as giving fair
samples of the deposits which now fill the lower parts
of the submerged valleys of Devon and Cornwall.
These valleys were all at one time long creeks or arms
of the sea, navigable for a considerable distance inland
and affording a fine series of sheltered harbours at
short distances apart A few of these harboui-s were
so deep and large that they have not yet been obliter-
ated, as is seen in the case of the Dart, the branches
of Plymouth Harbour, the Fal, the Gannel, etc. A
rapid silting-up is, however, now going on, greatly
aided by the refuse from the mines and china-clay

vii] CORNWALL AND ATLANTIC COAST 99

works. In the days whilst the subsidence was in
progress Cornwall was essentially a country of flords,
though now good harbours are few or blocked with
sandbanks.

The abundance of sheltered creeks must have had
considerable influence on the manner of living of the
inhabitants ; but it is noticeable that though many
acres of the silts have been removed in tinning, and a
good many human remains have been found, there is
no mention of boats. This absence of any record of
boats in any of the marine silts associated with or
below submerged forests cannot be an accident ; for
old boats and dug-out canoes are constantly being
discovered in later alluvial and fen deposits. It looks
as if in those early days man had either no boats, or
only used coracles of skin and wicker, such as would
entirely decay and leave no trace.

It may be remarked that the higher submerged
forest, that lying just about low- water level, is not
recorded in the deep excavations at Pentuan and
Carnon, though these old land-surfaces are so con-
spicuous on the foreshore opposite every smaller
creek, when the sea happens to scour away the sand
and beach. A little consideration will show the
reason of this difference. The extensive stream-works
of Pentuan and Carnon happen to lie at the mouths
of two of the larger and deeper creeks, in which
silting-up could not keep pace with the subsidence.

100 SUBMERGED FORESTS [ch.

Thus the seaward ends were continuously occupied by
sea, from the time when the oak-forest sank riglit on
into historic times, and over this deeply buried oak-
forest we only find alternate layers of silt and sea-sand.
Evidence of the later submerged forest, however, is
not entirely wanting, for the submerged wooden bridge
or causeway of Pentuan must belong to the period
Avhen the trees seen on the foreshore elsewhere Mere
flourishing well above high-water mark.

The submerged forests seen on the foreshore in
M'estern Cornwall are so like those exposed elsewhere
that there is no need for a full description, were it
not that they have become so connected with ancient
legends of Lost Lyonesse, a country which is supposed
to have joined the Land's End to the Isles of Scilly
somewhere about the date of King Arthur and Merlin.
To what extent these stories are due to observation
of the submerged forests and of the rapid waste of
land in Mount's Bay, supplemented by a vivid Celtic
imagination, which saw "the tops of houses througli
the clear water," is doubtful. Legend may assist, as is
shown in a later chapter (p. 120). One thing is clear,
the alluvial flat of Mount's Bay, under which the sub-
merged forest lies, formerly extended much further
seaward; and old writers mention the tradition that
St Michael's Mount formerly rose as an isolated rock
in a wood. As far as can be calculated from its
known rate of encroachment, the sea cannot have

VII] CORNWALL AND ATLANTIC COAST 101

reached the Mount till long after the Roman period,
and the legend is probably quite accurate. The Mount
was surrounded by a wide marshy flat covered with
alders and willows till well within the historic period;
the contradictory story, that the Phoenician traded
to St Michael's Mount for tin seems to be the inven-
tion of a sixteenth-century antiquary.

In Mount's Bay there has been subsidence as well
as loss of land through the attacks of the sea, for
beneath the alluvial plain, part of which is still seen
in Marazion Marsh, is buried a submerged forest.
Stumps of large oaks, as well as roots of hazel and
sallow, are to be seen at various points on the fore-
shore, where the overlying alluvium and peat have
been cleared away by the sea. But the oak-stumps
seem to be rooted on a soil resting directly on solid
rock ; they do not appear to be underlain by estuarine
deposits, or by lower submerged forests. This par-
ticular land-surface may therefore represent a long
period of gradual sinking, during which the trees
flourished continuously, and first at a considerable
elevation above the sea.

The deposit would repay closer examination, for
it was not well exposed while I was staying in Corn-
wall. I could find no trace of man in it at Penzance,
and the contained flora was principally noticeable for
its poverty and the entire absence of any of the
chamcteristic west-country plants. Tlie trees were

102 SUBMERGED FORESTS [CH.

the oak, liazel, and sallow, the seeds obtained belong
to the lesser spearwort, blackberry, a potentil, self-
heal, and some sedges.

Carne, however, in 1846 was more successful at the
eastern end of the Bay, for he has lianded down to us
an account of the strata met with in a mine-shaft on
Marazion INIarsh. The height of tlie ground at this
spot is only about 12 feet above mean-tide level, and
as tlie deposits penetrated are 32 feet thick, it is clear
that both the rocky floor and the lower peat must lie
beneath the level of the lowest spring tide. The
position of the shaft was close to the Marazion River,
Avhere we would expect also to find an ancient buried
channel. The upper deposits may be of very modern
date. Commencing at the top the succession met
with was : —

Feet
Slimo, gravel and loose ground ... 8

Recent estua- ( Rather soft peat 4

rine deposits | White sand with cockles 1"2

/ Layer of trees, principally oak and

Recent hazel, all prostrate. One piece of

or oak, about 14 feet long, appears to

Neolithic have been wrought, as if it had been

V intended for the keel of a boat ... 1 to 2
"Submerged j Hard solid peat, of closer texture than

forest" i the upper bed 3

Alluvial gravel with tin-ore 4

Slaty floor at 32

VII] CORNWALL AND ATLANTIC COAST 103

It will be observed that the supposed keel of a
boat occurs above the old land-surface, among drift-
wood which probably belongs to the first infilling of
the estuary after the submergence took place. The
upper peat is probably nothing but the surface of the
modern marsh, smothered and much compressed by
the eight feet of " loose ground " or refuse from the
neighbouring mines which had accumidated above it.
The cockles probably flourished at the same level
(about low- water mark) as that at which they are
noAv found.

It is not our intention here to deal in any detail
with the submerged land-surfaces noticed on the
French coast opposite. The Channel Islands yield
indications of submergence, and if its amount was
as great as that proved on the north shores of the
Channel, then the Channel Islands must have been
connected with the mainland up to a period when
the climatic conditions were similar to and the fauna
and flora resembled those of the adjoining parts of
France at the present day.

Further west, recent discoveries on the shores of
the Bay of Biscay are of considerable interest, for
submerged forests occur at various places, though
the maximum amount of the submergence has not
yet been satisfactorily made out.

One of the most interesting of the submerged
forests seen between tide-marks on the French coast

104 SUBMERGED FORESTS [ch.

was that discovered a few years since by Monsieur
Emil Gadeceau in Belle He. This island lies off the
month of the Loire, and its position some way from
the coast and well out in the Atlantic induced him
to make a special study of its flora. While engaged
in this, his attention was drawn to certain hard peaty
deposits seen only at low tide, and he asked me to
undertake the examination of the seeds found in
them. This work was gladly undertaken, as it carried
further south the examination which was then being
made into the flora of the submerged forests.

The results were somewhat surprising ; out of
about 30 species sufficiently Avell preserved for
identification, six were no longer living in Belle He,
though known in Western France. The whole flora
might have come from the north of England, charac-
teristic French species being entirely missing, though
this element is fairly represented in the living flora
of the island. In short, the flora is a northern one,
though in no degree arctic, and in this it agrees well
with the poor assemblage commonly found in the
submerged forests of the south of England.

From still further south, at various points on the
shores of the Bay of Biscay, and from the submerged
peaty deposits which underlie the Landes, seeds
have since been collected by my friend, Professor
Jules Welsch, of Poitiers. These also all belong
to conmiou living British plants, except that at

VIII] SUMMARY 105

Bretignolles, south of latitude 47^ we meet for the
first time oue characteristic southern plant — the vine.
Unfortunately the search for traces of man and his
works in these deposits has so far been unsuccessful,
and we cannot yet be certain therefore that they
are all of quite the same date, or correspond exactly
with the submerged forests of Britain.

CHAPTER VIII

SUMMARY

To what conclusions do the foregoing somewhat
monotonous pages lead ? Do they help us to explain
tlie origin of our fauna and flora? What light do
they throw on the antiquity of man in Britain, or
on the race problems that everywhere confront us?
Can the deposits therein described be in any way
connected with written history or with legend ? Do
they give us any approach to a measure of geological
time ? And, to what extent does the period of the
submerged forests tie on historical times with the
Glacial Epoch?

All these questions are connected with the subject-
matter of this little book ; but it is not written with
the idea of showing how much we know or pretend
to know. Our main object is to draw attention to a

106 SUBMERGED FORESTS [cH.

much neglected period in geological history and to
suggest directions in wliich further research is likely
to be profitable. We have, however, made out several
points, and can give an approximate answer to some
of the questions.

It is quite clear that at the opening of the period
with which this volume deals, the greater part of
England stood fully 70 feet above its present level,
for the oldest deposit we deal with is a land-surface
covered with oak-forest and lying 60 feet below tide-
level. The oaks cannot have flourished lower, but
they may have grown on a soil well above sea-level.
Perhaps taking the whole of the evidence into account,
a subsidence of nearly 90 feet is the most probable
measure of the extent of the subsequent movement.
We do not yet know whether in England this
movement was a depression of the land or a rise
of the sea; but the fact that the relative levels
seem to have been quite difterent in Scotland and in
Scandinavia seems to indicate that it was the land
that moved, not the sea.

We begin, therefore, with a period when the whole
of the southern part of the North Sea was an alluvial
flat connecting Britain with Holland and Denmark,
and to some extent with France. The Isle of Wight
was connected with Hampshire, and the Channel
Islands with France. Probably tlie Isles of Scilly
were islands even then, for the channel between them

VIII] SUMMARY 107

and Cornwall is both deep and wide, though this may
possibly be due to tidal scour.

The animals and plants yet known from this lowest
submerged forest are disappointingly few ; but the
prevalence of the oak shows that the climate was
mild, and that we have no clear indication of con-
ditions approaching to those of the Glacial Epoch. In
fact, in all the submerged forests the fauna and flora
seem poor and monotonous, consisting essentially of
living British species, with a few mammals since
locally exterminated by man, and all known to have
a wide range both in climate and latitude.

This in itself, however, is a point gained in the
study of the origin of our flora ; for though the de-
ficiency is no doubt largely due to insufficient col-
lecting, I am convinced that it is a true characteristic
of this period of transition. Much time has been
spent in examining and collecting the fossils of these
submerged forests, and various friends have also
worked at them ; but everywhere we seem to get
the same result, and many abandon the study be-
cause there is so little to show for it. The deposits
certainly contain a much poorer fauna and flora than
either the Pleistocene or the recent alluvial strata.

If we consider the Britain of the submerged
forests as having lately emerged from a time when
the climate was ungenial, we should naturally ex-
pect to find among the first incomers after the

108 SUBMElKiED FORESTS [ch.

change only such animals and plants as have a wide
climatic range or can migrate freely. It is these
species, and these only, -which will be living on the
neighbouring lands ; it is only an assemblage like
this that can stand the climatic alternations and
relapses that are likely to attend the transition.
An assemblage consisting only of species widely
distributed in latitude is probably an assemblage
that has special means of dispersal — even if we do
not happen yet to have discovered these means.

These considerations should lead us to expect to
find living, in any country which has lately undergone
a change of climate, a somewhat peculiar assemblage,
consisting mainly of hardy forms of Avide range in
latitude, and not characteristically either northern or
southern. Mingled with them, we might expect a few
survivors from the previous warm or cold period. A
liardy fauna and flora seem to characterise the period
of the submerged forests ; but the absence or great
scarcitv of characteristic survivors from a former
period suggests that even the lowest of these de-
posits is far removed from the Glacial Epoch. The
arctic species had already had time to die out, or
had been crowded out ; but the time had not been
sufliciently long for the incoming of the southern
forms which now characterise our southern counties.
Then, even less than now, had we reached a i>crfect
adjustment of the fauna and flora to the climatic

viiij SUMMARY 109

conditions; this can only be broughtabout by a constant
invasion of species from all the surrounding regions.
Some hold their own, most cannot; but as time goes
o!), the surviving assemblage consists more and more
of species which have been able to fight against the
severe competition and colonize a new country.

Garden experiments are of little use as tests of
the capability of any plant to survive in this country ;
the study of cornfield weeds is no better. In both
cases the cultivation of the land produces a bare
place on which a foreign introduction has as good
a chance as a native. But could this foreigner sur-
vive if the seed were dropped on a natural moor or
meadow ? In this connexion it is noticeable that
great part of the rare British plants occur close to
the coast, opposite the part of the continent in which
they are found, though they are not maritime species.
This is probably due to two different causes, both
acting in the same direction. In the first place most
of these local plants are obviously late comers, which
have not yet had time to spread iidand or far. And,
secondly, on the coast alone do we find any consider-
able extent of natural bare land —practically garden
land — which does not at the same time consist of
poor soil. The tumbled undercliffs of our coast are
just the places to give a foreign invader a chance ;
there only will it find patches of bare good soil, full
of small cracks in which a seed is hidden from birds.

no SUBMERGED FORESTS [CH.

If the vieAV is correct, that a continuous growth
of our flora, and to some extent of our fauna, takes
place through transportation to our coasts, from
which such species as can fight their way tend more
slowly to spread inland, it seems to account for the
present curious distribution of species, and this in a
way that no continuous land-connexion will do.

As we have pointed out in a former chapter, the
land-connexion across the North Sea was a wide
alluvial plain and swampy delta. What use could
dry-soil plants make of such a bridge ? It would be
no easier for them to cross than so much sea; and
migrating mammals could not greatly help in the
dispersal, wiiere so many rivers had to be crossed.
The aquatic species would be helped by such a con-
nexion, and it is curious to note that several of
our most interesting aquatic plants are confined to
the eastern counties, which in post-glacial times had
direct connexion with the delta of the Rhine, and
probably with the Elbe.

Aquatic species, however, are not dependent on
continuous waterways for their dispersal; they have
great facilities for overleaping barriers and reaching
isolated river-basins and lakes. Every dew-pond on
the downs after a few years' existence contains aquatic
plants and mollusca, and a still larger number of
species, including fish, will be found in ancient flooded
quarries or prehistoric dykes surrounding some

VIII] SUMMARY 111

hill-fortification. If an aquatic plant is fairly
common on the continent near by, it is almost
certain to occur in some isolated pond or river in
the part of Britain opposite.

Many of our peculiar mollusca and plants are
limestone species, which must have crossed over at
a single leap, for no elevation or depression will
connect the various isolated limestone masses of
Britain. A i)ost-glacial elevation would connect the
North Downs with the corresponding chalk-hills of
France ; but these Downs are isolated by wide tracts
of non-calcareous strata from the areas of Oolite or
Carboniferous limestone to which many of our lime-
stone animals and plants are now confined. There
is also nothing in the present distribution of our
limestone si)ecies to suggest that any great stream
of migrants used this bridge of chalk-downs.

It may be asked, \Miy discuss these questions here,
if all these peculiar species are unknown in the sub-
merged forests ? In certain cases negative evidence
is of great value, and the deficient flora of the sub-
merged forests is a case in point. We find a striking
contrast between this ancient flora and the flora which
flourished when cultivation of the land had begun.
The Roman deposits in Britain yield many species
which have not yet been found in the submerged
forests, and even the earlier Celtic deposits have
already yielded a few of them. To a large extent

112 SUBMERGED FORESTS [ch.

this difference is due to the agency of man, in-
tentional to a certain extent, but mainly accidental,
through the introduction of weeds and the prepara-
tion of the soil for crops. It must not be forgotten
that man not only introduced the weeds, he prepared
the land on which they could establish themselves,
and from thence spread to uncultivated ground where
few botanists now suspect that they are anything but
" native."

In days when the people of Britain were hunters,
the only extensive open country in the south and
east seems to have been the chalk-doAvns and the
sandy heaths. These were not suitable for new ad-
ditions to the plant population, for the good land
was all oak forest, the ))arren heaths were unfavour-
able for any but heath plants, and the alluvial flats
were largely covered with sallow and alder. The
open downs were clothed with close turf, and until
this was broken by cultivation there would be little
chance for migrants. It seems, therefore, that to
obtain a clear idea of the plant population of this
country before man's influence could be felt, we
must study the flora of the submerged forests and
of the associated alluvial detritus washed from the
uplands during the same period. Till this is done
more thoroughly, it is not much use to discuss what
species are "native" and wliat "introduced"; the sub-
merged forest will yield the answer to this question.

VIII] SUMMARY 113

The next question we have put — What light do
these submerged forests throw on the anticfuity of
man in Britain, or on the race-i)roblems of Britain? —
is a difficult one to answer in the present state of our
knowledge. Valuable evidence has been lost through
the failure to preserve most of the human remains
that have been found ; but both Owen and Huxlev
recognised the peculiar type of the "river-drift man."
Unfortunately few implements have been collected,
and the pieces of wood shaped by man, though re-
corded, have not been preserved. One implement of
polished stone has certainly been found in the latest
submerged land-surface, but it is not clear that any
thing except flakes has been obtained in the older
deposits. Still the stratigraphical relations seem to
indicate that all these deposits are of Neolithic age
and later than the Palaeolithic terraces. The re-
lations of Palaeolithic to Neolithic are still very
obscure in this country, and the reason is perhaps
to be sought in a submergence which has tended to
carry many of the transition deposits beneath the
sea-level, or has caused them to be silted up under
more modern alluvium. The lowest submerged forest
requires careful search before we can be certain of its
true position in the sequence ; but it is seldom exposed,
and then only in dock-excavations soon again hidden.

Before we can attempt to answer the other
questions, it is important to get an estimate of the

K. 8

114 SUBMERGED FORESTS [ch.

amount of time occupied in the fonnation of these
deposits, and of tlie lapse of time since the last
of them was formed. The newest of them belongs
certainly to the age of polished stone, and the earliest
also probably comes within the Neolithic period. We
have already seen that within the period represented
by the submerged forests there has been a rise of the
sea-level, or depression of the land, to the extent of
80 feet, perhaps a few feet more. If we can obtain
some measure of the time occupied in the formation
of such a series of deposits, this should give us some
idea as to the length of the Neolithic period, and
also of the rate at which changes of the sea-level
sometimes can take place.

It is unfortunate that for these calculations so
many of the factors are of uncertain value. We
may estimate from the present rate of erosion of
the coast the amount that has been lost since the
sea-level became stationary, or we may take the rate
of accumulation of sand-dunes or shingle-spits ; or
the rate at which our estuaries, harbours, and broads
are silting up. It all comes, however, to this — no
exact figures can be given ; but so many rough cal-
culations lead to approximately the same date, that
the date arrived at may be trusted to give some idea
of the length of the period M'hich has elapsed since
the downward movement ceased.

Working backwards from the present day, step by

VIII] SUMMARY 115

step, archaeological evidence gives an undoubted
period of 2000 years, to the first century B.C., during
which no measurable change of sea-level has taken
place in the south of England.

To this must be added a few centuries for the
growth of the marshes on which Glastonbury and
similar lake-dwellings were built, and for the growth
of various other marshes at present sea-level known
to be earlier than the Roman invasion. Also we
must allow for the accumulation of various shingle-
spits and sand-dunes then already partly formed.

In general, somewhere about one-third or one-
half of this accumulation seems to have taken place
before the Roman invasion. This adds another 1500
years ; so that -about 3500 years ago, we get back to
the beginning of the period of unchanging sea-level
in which we are still living, and begin to see evidence
of earth movements still in progress.

Whether this 3500 years will take us back to the
beginning of the Bronze Age in Britain is not yet
proved ; but so far we seem to discover metals in the
whole of the deposits formed whilst the sea-level re-
mained unchanged, and only stone weapons in even
the newest of the submerged forests. For the present,
we may therefore take it that the two changes nearly
coincided. The use of metals began in Britain about
the time that the earth-movements ceased — that
is to say somewhere about 1600 B.C.

8—2

11(3 SUBMPJRGEI) FORESTS [CH.

Whether this period of 3500 years will really take
us back to the commencement of the Bronze Age is
doubtful, for Stonehenge had already been built, and
though onlv stone hammers seem to have been there
used, yet one slight streak of bronze or copper has
been noticed. Of course, there may have been a
similar occasional use of bronze at the time of the
last submerged forest ; but we have as yet no evidence
of this, and the possible correspondence in date
between Stonehenge and the last of the submerged
forests remains merely a suggestion.

Perhaps we may still find submerged stone-circles
or other antiquities of the age of Stonehenge beneath
the sea-level ; but Stonehenge lies too high above the
sea for it in itself to give any clue as to a change of
sea-level. We will only make one suggestion. It is
probable that when Stonehenge was built, a long arm
of the sea extended far up the Avon Valley, so that
navigable water was found not far from Stonehenge.
There is in Stonehenge an inner circle of smaller
stones, not composed of the local greywethers but
consisting of large blocks of igneous rock of foreign
origin. These blocks, which are sufficiently large to
be awkward for land-carriage, have been said to be
erratics gathered on Salisbury Plain, just as the
grey- wethers for the main circle were gathered ; but
there are no erratics on Salisbury Plain. Large
erratic blocks of similar character occur, however,

VIII] SUMMARY 117

abundantly on the lowlands of Selsey Bill, under the
lee of the Isle of Wight. Probably a similar erratic-
strewn plain once fringed the coast on the west
also, though on the exposed side the part above the
sea-level has now been entirely swept away by the
sea.

I would suggest that the Stonehenge erratics,
instead of being brought from any great distance,
may have come from a wide plain at the mouth of the
Avon, then two or three miles further seaward. From
thence they were rafted far up the navigable fjord,
not yet silted up, and Avere only carried a short
distance uphill. Igneous rocks such as these, found
in a country consisting essentially of chalk and
Tertiary strata, would be valuable and probably en-
dowed with magic properties, hence their employ-
ment in this inner circle.

Our next enquiry must be into tlic length of time
represented by the series of submerged forests and
associated deposits described in the foregoing pages.
The newest of them belongs certainly to the age of
polished stone, and the earliest also probably comes
withhi the Neolithic Period. Within the period
represented by the submerged forests, we have seen
that there has been a change of the sea-level to the
extent of 80 feet, or perhaps rather more. If yfe can
obtain some measure of the time occupied, this should
give us some approximate idea as to the length of

118 SUBMERGED FORESTS [ch.

the Neolithic period, and of the rate at which changes
of the sea-level can take place.

The first point to be considered is the length
of time occupied by the growth of the series of
submerged forests. On first examining, or reading
accounts of, deposits of this sort one obtains a vague
impression of long periods, during which mighty oaks
flourished. Both the movements of submergence and
the intervening periods of vegetable growth seem to
require great lapses of time. On closer study, how-
ever, the evidence seems scarcely to support this
view, for estuarine silts are deposits of exceptionally
rapid gi'owth, and one finds that the usual character-
istic of a " submerged forest " is that it shows indica-
tions of only a single generation of trees. The trees
also are usually small, except where the submerged
forest rests directly on deposits of much earlier date,
or on solid rock.

It should be remembered that the large oak trees
which are often found in the lowest land-surface at
any particular place do not necessarily belong to any
one special stage of the submergence. These same
trees may have grown continuously above tide-
marks during several successive stages, until at
last the upward creeping water rose sufficiently
to reach this part of the forest. The large well-
grown oaks seen in Mount's Bay and various other
places are, as far as I have seen, all rooted on

VIII] SUMMARY 119

ancient gravels, solid rock, or boulder clay, not on
beds of silt.

We cannot speak confidently as to the time needed
to form each thin layer of vegetable soil, marsh peat,
or estuarine silt. On comparing the submerged land-
surfaces, however, with similar accumulations formed
within known periods, such as marsh soils grown
behind ancient embankments, or forest-growth over
flats silted up at known dates, we can learn some-
thing. No one of the land-surfaces alternating with
the silts would necessarily require more than a century
or two for its formation. Brushwood and swamp
growth are the characteristic features of these de-
posits, and such growth accumulates and decays very
rapidly. Possibly trees of older growth may still
be found, but I have not succeeded in discovering
a tree more than a century old in any one of the
marsh deposits alternating with the estuarine silts.
Oaks of three centuries may be observed rooted in
the older deposits; but this, as above explained, is
another matter.

It is useless to pretend to any exact calculations
as to the time needed for the formation of these
alternating strata of estuarine silt and marsh -soil ;
but looking at the whole of the evidence without bias
either way, it seems that an allowance of 1000, or at
most 1500, years would be ample time to allow. A
period of loOO years may therefore be taken to cover

120 SUBMERGED FORESTS [ch.

the whole of the changes winch took place during the
period of gradual submergence.

If this is approximately correct, the date at which
the submergence began was only 5000 years ago, or
about 3000 B.C. The estimate may have to be modi-
fied as we obtain better evidence ; but it is as well to
realize clearly that we are not dealing with a long
period, of great geological antiquity ; we are dealing
with times when the Egyptian, Babylonian, and
Minoan civilizations flourished. Northern Europe
was then probably barbarous, and metals had not
come into use; but the amber trade of the Baltic
was probably in full swing. Rumours of any great
disaster, such as the submergence of thousands of
square miles and the displacement of large popula-
tions might spread far and wide along the tmde
routes. Is it possible that thus originated some of
the stories of the deluge ?

We will not now pursue this enquiry; but it is
well to bear in mind the probability that here geology,
archaeology, and history meet and overlap. Any day
one of our submerged forests may yield some article
of Egyptian manufacture of known date, such as a
scarab, which has passed from hand to hand along
the ancient trade routes, till it reached a country
still living in the Stone Age, M'here its only use would
be in magic, lint it might now serve to give us a de-
finite date for one of these submerged forests. It

VIII] SUMMARY 121

might happen to have been lost with some of the
stone implements, or with one of the human skeletons,
apparently belonging to persons drowned, for no trace
of a grave is ever mentioned. A find of this sort is
no more improbable than the discovery of a useless
modern revolver in a bag of stone and bone tools
belonging to some Esquimaux far beyond the reach
of ordinary civilized races.

In this connexion it might be worth while sys-
tematically to dredge the Dogger Bank, in order to
see whether any implements made by man can be
found there. The alluvial deposits are there so free
from stones that if any at all are found in them they
may probably show human workmanship. The Dogger
Bank may have remained an island long after great
part of the bed of the North Sea had been submerged,
for the Bank now forms a submerged plateau. It
may even have lasted into fairly recent times, the
final destruction of the island being due to the
planing away of the upper part of the soft alluvial
strata through the attacks of the sea and of boring
molluscs. Pholas is now actively attacking the hard
peat-beds at a depth of more than 10 fathoms, and is
rapidly destroying this accumulation of moorlog,
wherever the tidal scour is sufficient to lay it bare.

8—5

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Notes on the Geological Position of the Human Skeleton

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INDEX

Alder, 1, 8, 16, 32, 04, 112

Alternations of freshwater and
marine strata, 4, 7, 10, 29, 3-5,
44, 51, 57, 94-97

Amberley Wild Brook, 73

Amsterdam, 48

Anchor- ice, 89

Aquatic plants, dispersal of, 110

Archaeological evidence, 61, 115-
117, 121

Atlantic waves, effect of, 85, 86

Baltic, 49

Barrv Docks, 52-57, 59

Base-level planes, 22, 37, 38, 80,

87, 88
Baynes, D., 13-17
Bay of Biscay, 86, 103-105
Bear, 2

Beaver, 2, 35, 44
Belle He, 104
Bideford Bay, 61, 62
Birch, arctic, 46

white, 46

Blakeney, 29
Boar, 2, 35
Boats, 99, 102, 103
Bog-bean, 45
Bone needles, 54
Br^tigr.olles, 104
Brirlgwater Levels, 60
Bristol Channel, 58-61
Broadri, 23-26, 114
Briigger, W. C, 122
Bron/.e age, 115, 116, 120

Caesar's invasion, 65, 60, 75

Canoes, 99, 102, 103

Cardiff, 57

Carne, J., 102

Carnon stream-works, 98, 99

Cattewater, 84, 88

Causeway, submerged, 97, 100

Celtic shorthorn, 63, 96

Champion, G. C, 46

Channel Islands, 68, 86, 103,

106
Channels, shifting of, 6, 21, 36,

37, 91, 93, 102
Chara-marl, 8
Charcoal below submerged forest,

97
Chatteris, 30, 35
Cheshire, 50, 51, frontispiece
Chichester Harbour, 76, 77
Clacton, 21, 23, 30, 31
Climatic changes, 10, 46, 00-68,

104, 107, 108
Clyde-beds, 50
Coast-erosion, 114
Colenso, J. W., 91-97, 122
Compression of alluvial strata,

3, 4, 16
Continental platform, origin of

the, 69, 70
Coracles, 99
Corbicula fiuminnlh, 11, 23, 31,

35, 37, 74
Cornel, 55
Cornwall, 80-105
Cotoneaitter Pyracanthu, 74

126

INDEX

Cromer Forest-bed, 11, 22, 23,

39
Cultivation, effects of. 111, 112

Dart, 98

Dartmoor, 82, 83, 89

Dates, 26, 114-121

Dead Sea depressions, 5

Dee, 51

Deformation of shore-lines, 88,49

Deluge, 2, 66, 81, 120

Denmark, 48, 106

Depression, extent of, 8, 17, 20,

22. 26, 38, 47-49, 51, 56, 57,

68, 73, 75, 88, 93, 94, 106
Devonport, 6, 83, 90
Dispersal of plants, 108, 109-

112
Dogger Bank, 17, 18, 39-49, 69,

121, 124
Domestic animals, 63, 96
Dove Point, 50, 51, frontispiece
Dunge Ness, 71

Eccles Church, 27, 28

Elbe, 40, 110

Elder, 16

Elevation of the land, former, 8,

17, 20, 22, 26, 38, 47-49, 51,

56, 57, 68, 73, 75, 106
Elwes, J. W., 124
Ely, 30, 34

English Channel, 64-79
Estuaries, siltiug-up of, 25, 26,

114

Fal, 98
Fareham, 76

Fen-depof'its, 30-36, 44, 45
Fenland, 4, 30-37
Flint-implements, 21, 35, 54, 62,
74, 113

Flora, changes of the, 9, 10, 110

of tlie submerged forests,

63, 64, 1(»4, 105, 107, 108

Formby, 52
France, 103-106

Gadeceau, E., 104

Gannel, 98

Geographical distribution, 60, 110

Glacial epoch, 10, 23, 36, 67, 68,

83, 87, 89, 90, 94, 107, 108
Glamorgan, 52-57
Glastonbury Levels, 60-62, 115
Godwin-Austen, R. A. C, 122
Gold-dust, 92

Goodchild, H. H.. 42, 124
Goodwin Sands, 66, 70
Gothland, 49
Gravesend, 17
Grays, 20, 23, 30, 31, 37

Hamoaze, 84, 85, 88
Hampshire, 74-79, 106
Happisburgh, 39
Happy Union, 92-97
Harbours, origin of, 77, 78

silting-up of, 98, 99, 114

Harwich, 22

Hastings, 71

Hawthorn, 55

Hazel, 1, 8, 9, 46, 55, 98, 101,

102
Henwood, W. J., 98, 123
Heysham, 50
Holderness, 38, 44
Holland, 4, 44, 48, 49, 106
Holmes, T. V., 123
Horse Sand Fort, 74
Human remains, 9, 10, 13-15,

17, 18, 52, 62, 96-99, 11.-5, 121
Hiimber, 20, 35-38, 88
Huxlcv, Prof. T., 13, 15. 113

INDEX

127

Implements, stone, 21, 35, 54,
62, 74, 113

wooden, 96, 113

Intermittent depression, 35, 51
Ireland, 49

Irish elk, 21

Sea, 80

Isle of Man, 50

Wight, 75, 76, 106, 117

Keith, Prof. A., 13, 15, 122
Kent, 65-70
Kessingland, 23
King. Rev. S. W., 27
King's Lynn, 6

Laira Viaduct, 88
Lancashire, 50, 51
Landes, 104
Land's End, 100
Landslips, 3
Langer Fort, 22
Langston Harbour, 76, 77
Leasowe, 50, 51, frontispiece
Lewes, 73
Lincolnshire, 35
London, 12, 19
Lorie, Dr J., 122
Lost Lyon esse, 100
Lowestoft, 23, 26
Lyell, Sir C, 27, 91

Mammoth, 15, 21, 35
Man, remains of, 9, 10, 13-15,
17, 18, 52, 62, 96-99, 113, 121
Man's influence on our flora, 112
Marazion, 101-103
March, 30, 31, 35, 37
Marine erosion, 84-86
Mersey, 51, 52

Migration of species, 10, 108-112
Miller, S. H., 122

Moorlog, 41, 43, 44, 47
Morton, G. H., 123
Mosses, formation of, 35
Mount's Bay, 100, 101, 118
Munthe, Dr H., 49, 123

Najas marina, 53

Nar Vallev Beds, 31, 35

Neolithic, 21, 35, 38, 53, 62, 74,

75, 79, 113-115, 118
Noah's Woods, 1, 66
Noman Fort, 75
Norfolk broads, 23, 24-26, 49
North Sea, 17, 38-49, 67, 68, 80,

106, 110, 121
Norway, 49

Oak, 1, 8, 16, 19, 32, 34, 54-57,
62, 71, 94-96, 101, 102, 106,

107, 119, 120

cut by man, 97

Osmnvda, 1, 52

Ouse, 6

Owen, Sir R., 13, 15, 18, 113,

123
Oysters on submerged trees, 94,
■95

Palaeolithic, 15, 21, 22, 113

Pegwell Bay, 65

Pentuan, 92-97, 99, 100, 122

Penzance, 101

Pepys, S., 19

Pevensey Level, 71

Pholas, erosion caused bv, 43,

121
Piles below a submerged forest,

97, 100
Pine, 32, 34, 35, 79
Plane of marine denudation, 22
Plym, 82
Plymouth Sound, 83-88, 90, 98

128

INDEX

Polished stone implements, 54,

113
Pollen-grains in submerged peat,

45
Poole Harbour, 79
Portsmouth Harbour, 76, 77
Potter, C, 123
Potter Heigham, 26
Prestwich, Sir J., 26, 123
Prevost, Dr E. W., 123

Raised beaches, 38, 50
Eashleigli, P., 123
lleade, T. M., 50, 51, 123
Reindeer, 44, 79
Rhine, 18, 40, 67, 110
Ribble. 51
River-drift man, 15

ice, 89

Roadway, submerged, 28, 100

Rogers,!., 61, 62, 124

Roman period, 3, 16, 61, 63, 65,

75, 101, 111, 115
Romoey Marsh, 70, 71
Rostock, 49
Ihippia, 46

St Austell River, 92-98

St Michael's Mount, 100, 101

Saltash, 88

Sand-dunes, 3-5, 26, 27, 47, 114

Sangatte, 68

Scandinavia, 49, 106

Scillv, 100, 106

Scotland, 38, 49, 50, 106

Scrohiculariii-clay, 7, 19, 53, 96

Sea-level, changes of, 3, 4, 8,
17-20, 22, 26, 38, 47, 48, 51,
57, 68, 73, 75, 100, 114

Selsey, 74, 117

Severn Tunnel, 59

Sheep, 63

Shell-marl, 8
Sherringham, 22
Shingle -beach, protection af-
forded by, 3-5

spits, growth of, 26, 114

Shore, T. W., 79, 124
Silting-up, rate of, 25, 26
Skertchly, S. B. .7., 31, 122, 124
Solent, 74-76

Somerset, 60, 61

Southampton Water, 74, 76, 79

South Downs, 72

Southwold, 22

Spithead, 74-77

Spurrell, F. C. J., 13, 15-18, 124

Stathor, J. W., 124

Stonehenge, 116

Storrie, J., 53, 54

Strahan, Dr A., 52-57, 124

Strait of Dover, 6.5-70

Stream-tin works, 80, 81, 90-102,

123, 124
Submarine erosion, 69, 84-86,

121
Submerged forest, definition of,

11
Submergence, extent of the, 8,

17, 20, 22, 26, 38, 47-49, 51, 56,

57, 68, 73, 75, 88, 93, 94, 106
Sussex, 65, 68, 71-74
Sweden, 49

Tamar, 82, 84, 85

Tavy. 82, 88

Thames, 11-19, 20, 21. 29. 38,

40, 51, 52, 84, 88. 122, 124
Thaws and floods, 89
Tidal scour, 69. 85, 86

wave deadened by obstruc-
tions, 4, 5. 28, 29

Tides of the Bristol Channel, .56
Tilbury, i:i-19

INDEX

129

Time 114-121 WealJeii axis, 72

Tiu stream-works, 80, 81, 90-1U2, Weeds, iutroduction of, 112

123, 124 Welsch, Prof. J., 104

Trees growing below high-water Westward Ho, 61-64

level, 4, 5, 8

rooted into rock, 4

succession of, 8, 32

Tyler, A., 124

Vegetable remains, decay of, 4
Vine, 105
Viigin, Wheal, 97

Walrus, 44

Wash, 29, 30

Waves, effect of, 85, 86

Wey bourn, 29

Whitaker, W., 13, 15, 16, 124

Whitehead, H., 42, 124

Wolf, 2, 35

Wood, implements of, 9, 96, 97,

113
Worth, K. H., 124

Yarmouth, Isle of Wight, 75

Norfolk, 26, 28

Yew, 19, 32

CAMBRIDGE ; PHINTED BY JOHN CLAY, 31. A. AX THK ONIVKRSII'Y PRESS

THE

CAMBRIDGE MANUALS
OF SCIENCE AND LITERATURE

Published by the Cambridge University Press
GENERAL EDITORS

P. GILES, Litt.D.

Master of Emmanuel College

and
A. C. SEWARD. M.A., F.R.S.

Professor of Botany in the University of Cambridge

70 VOLUMES NOW READY
HISTORY AND ARCHAEOLOGY

Ancient Assyria. By Rev. C. H. W. Johns, Litt.D.

Ancient Babylonia. By Rev. C. H. W. Johns, Litt.D.

A History of Civilization in Palestine. By Prof. R. A. S.

Macalister, M.A., F.S.A.
China and the Manchus. By Prof. H. A. Giles. LL.D.
1 he Civilization of Ancient Mexico. By Lewis Spence.
The Vikings. By Prof. Allen Mawer, M.A.
New Zealand. By the Hon. Sir Robert Stout, K.C.M.G., LL.D..

and J. Logan Stout, LL.B. (N.Z.).
The Ground Plan of the English Parish Church. By A.

Hamilton Thompson, M.A., F.S.A.
The Historical Growth of the English Parish Church. By A.

Hamilton Thompson. M.A.. F.S.A.
English Monasteries. By A. H. Thompson, M.A.. F.S.A.
Brasses. By J. S. M. Ward, B.A., F.R.Hist.S.
Ancient Stained and Painted Glass. By F. S. Eden.

ECONOMICS

Co-partnership in Industry. By C. R. Fay, M.A.

Cash and Credit. By D. A. Barker.

The Theory of Money. By D. A. Barker.

LITERARY HISTORY

The Early Religious Poetry of the Hebrews. By the Rev.

E. G. King, D.D.
The Early Religious Poetry of Persia. By the Rev. Prof. J.

Hope Moulton, D.D., D.Theol. (Berlin).
The History of the English Bible. By John Brown, D.D.
English Dialects from the Eighth Century to the Present Day.

By W. W. Skeat, Litt.D., D.C.L., F.B.A.
King Arthur in History and Legend. By Prof. W. Lewis

Jones, M.A.
The Icelandic Sagas. By W. A. Craigie, LL.D.
Greek Tragedy. By J. T. Sheppard, MA.
The Ballad in Literature. By T. F. Henderson.
Goethe and the Twentieth Century. By Prof. J. G. Robertson,

M.A., Ph.D.
The Troubadours. By the Rev. H. J. Chaytor, M.A.
Mysticism in English Literature. By Miss C. F. E. Spurgeon.

PHILOSOPHY AND RELIGION

The Idea of God in Early Religions. By Dr F. B. Jevons.

Comparative Religion. By Dr F. B. Jevons.

Plato : Moral and Political Ideals. By Mrs A. M. Adam.

The Moral Life and Moral Worth. By Prof. Sorley, Litt.D.

The English Puritans. By John Brown. D.D.

An Historical Account of the Rise and Development of Presby-

terianism in Scotland. By the Rt Hon. the Lord Balfour

of Burleigh. K.T., G.C.M.G.
Methodism. By Rev. H. B. Workman, D.Lit.

EDUCATION

Life in the Medieval University. By R. S. Rait, M.A.

LAW

The Administration of Justice in Criminal Matters (in England
and Wales). By G. Glover Alexander. M.A.. LL.M.

BIOLOGY

The Coming of Evolution. By Prof. J. W. Judd, C.B., F.R.S.
Heredity in the Light of Recent Research. By L. Doncaster,

M.A.
Primitive Animals. By Geoffrey Smith, M.A.
The Individual in the Animal Kingdom. By J. 5. Huxley, B.A.
Life in the Sea. By James Johnstone, B.Sc.
The Migration of Birds. By T. A. Coward.

BIOLOGY (continued)

Spiders. By C. Warburton, M.A.

Bees and Wasps. By O. H. Latter, M.A.

House Flies. By C. G. Hewitt, D.Sc.

Earthworms and their Allies. By F. E. Beddard, F.R.S.

The Wanderings of Animals. By H. F. Gadow, F.R.S.

ANTHROPOLOGY

The Wanderings of Peoples. By Dr A. C. Haddon, F.R.S.
Prehistoric Man. By Dr W. L. H. Duckworth.

GEOLOGY

Rocks and their Origins. By Prof. Grenville A. J. Cole.
The Work of Rain and Rivers. By T. G. Bonney, Sc.D.
The Natural History of Coal. By Dr E. A. Newell Arber.
The Natural History of Clay. By Alfred B. Searle.
The Origin of Earthquakes. By C. Davison, Sc.D., F.G.S.
Submerged Forests. By Clement Reid, F.R.S.

BOTANY

Plant-Animals : a Study in Symbiosis. By Prof. F. W. Keeble.
Plant-Life on Land. By Prof. F. O. Bower. Sc.D.. F.R.S.
Links with the Past in the Plant-World. By Prof. A. C. Seward.

PHYSICS

The Earth. By Prof. J. H. Poynting, F.R.S.
The Atmosphere. By A. J. Berry, M.A.
Beyond the Atom. By John Cox, M.A.
The Physical Basis of Music. By A. Wood. M.A.

PSYCHOLOGY

An Introduction to Experimental Psychology. By Dr C. S.

Myers.
The Psychology of Insanity. By Bernard Hart, M.D.

INDUSTRIAL AND MECHANICAL SCIENCE

The Modern Locomotive. By C. Edgar Allen. A.M.I.Mech.E.

The Modern Warship. By E. L. Attwood.

Aerial Locomotion. By E. H. Harper. M.A., and Allan E.

Ferguson, B.Sc.
Electricity in Locomotion. By A. G. Whyte. B.Sc.
Wireless Telegraphy. By Prof. C. L. Fortescue, M.A.
The Story of a Loaf of Bread. By Prof. T. B. Wood. M.A.
Brewing. By A. Chaston Chapman. F.I.C.

SOME VOLUMES IN PREPARATION
HISTORY AND ARCHAEOLOGY

The Aryans. By Prof. M. Winternitz.

Ancient India. By Prof. E. J. Rapson, M.A.

The Peoples of India. By J. D. Anderson, M.A.

The Balkan Peoples. By J. D. Bourchier.

Canada of the present day. By C. G. Hewitt, D.Sc.

The Evolution of Japan. By Prof. J. H. Longford.

The West Indieci. By Sir Daniel Morris, K.C.M.G.

The Royal Navy. By John Leyland.

Gypsies. By John Sampson.

A Grammar of Heraldry. By W. H. St John Hope, Lilt.D.

Celtic Art. By Joseph Anderson, LL.D.

ECONOMICS

Women's Work. By Miss Constance Smith,

LITERARY HISTORY

Early Indian Poetry. By A. A. Macdonell.

The Book. By H. G. Aldis, M.A.

Pantomime. By D. L. Murray.

Folk Song and Dance. By Miss Neal and F. Kidson.

PHYSICS

The Natural Sources of Energy. By Prof. A. H. Gibson, D.Sc.

The Sun. By Prof. R. A. Sampson.

Rontgen Rays. By Prof. W. H. Bragg, F.R.S.

BIOLOGY

The Life-story of Insects. By Prof. G. H. Carpenter.
The Flea. By H. Russell.
Pearls. By Prof. W. J. Dakin.

GEOLOGY

Soil Fertility. By E. J. Russell, D.Sc.
Coast Erosion. By Prof. T. J. Jehu.

INDUSTRIAL AND MECHANICAL SCIENCE

Coal Mining. By T. C. Cantrill.
Leather. By Prof. H. R. Procter.

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